Methods and devices for treating atrial fibrillation

ABSTRACT

Described here are systems and methods for affecting tissue within a body to form a lesion. Some systems comprise tissue-affecting devices, devices that guide the advancement of the tissue-affecting elements to a target tissue region, devices that locate and secure tissue, and devices that help position the tissue-affecting devices along the target tissue. The methods described here comprise advancing a first tissue-affecting device to a first surface of a target tissue, advancing a second tissue-affecting device to a second surface of the target tissue, and positioning the first and second devices so that a lesion may be formed in the tissue between them. In some variations, the devices, systems, and methods described here are used to treat atrial fibrillation by ablating fibrillating tissue from an endocardial surface and an epicardial surface of a heart. Methods of closing, occluding, and/or removing the left atrial appendage are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 61/323,796 filed Apr. 13, 2010, U.S.Provisional Patent Application No. 61/323,801 filed Apr. 13, 2010, andU.S. Provisional Patent Application No. 61/323,816 filed Apr. 13, 2010,the disclosures of each of which is hereby incorporated by reference inits entirety.

BACKGROUND

It is well documented that atrial fibrillation, either alone or as aconsequence of other cardiac disease, continues to persist as the mostcommon cardiac arrhythmia. Atrial fibrillation may be treated usingseveral methods, including administering anti-arrhythmic medications,and chemical and/or electrical cardioversion. Ablation of cardiac tissueusing surgical techniques have also been developed for atrialfibrillation, such as procedures for atrial isolation and ablation ofmacroreentrant circuits in the atria. For example, the MAZE IIIprocedure creates an electrical “maze” of non-conductive tissue in theatrium that acts to prevent the ability of the atria to fibrillate bycreating incisions in certain regions of atrial tissue. In some cases,the MAZE III procedure may include the electrical isolation of thepulmonary veins. While the MAZE III procedure has shown some efficacy intreating medically refractory atrial fibrillation, additional devicesand methods of treatment are desirable, especially if they provideadvantages over existing techniques.

BRIEF SUMMARY

Described here are devices, systems, and methods for affecting tissuewithin a body to form a lesion. Some systems may comprise devices havingtissue-affecting elements that are configured to be positioned onopposite sides of a tissue and operated simultaneously to form a lesionin the tissue between them. Some systems may also comprise devices thatguide the advancement of the tissue-affecting elements to a targettissue region, devices that locate and secure tissue, devices thatprovide access to the target tissue, and/or devices that may helpposition the tissue-affecting elements on one or more surfaces of thetarget tissue. The methods described here may utilize one or more ofthese devices, and generally comprise advancing a first tissue-affectingdevice to a first surface of a target tissue, advancing a secondtissue-affecting device to a second surface of the target tissue, andpositioning the first and second devices so that a lesion may be formedin the tissue between them. In some variations, the devices, systems,and methods described here may be used to treat atrial fibrillation byablating fibrillating tissue from an endocardial surface and anepicardial surface of an atrium of a heart. Methods of closing,occluding, and/or removing a portion of the target tissue (e.g., theleft atrial appendage) are also described.

One variation of a system for affecting tissue within a body maycomprise a first device and a second corresponding device. The first andsecond devices may each comprise an elongate member and one or moretissue-affecting elements. The one or more tissue-affecting elements ofthe second device may correspond to the tissue-affecting elements of thefirst device. In some variations, the first device may be configured tobe placed on a first surface of a target tissue, and the second devicemay be configured to be placed on a second surface of the target tissue,where the second surface is opposite the first surface. The first andsecond devices may be configured to operate the tissue-affectingelements simultaneously to form a lesion in the target tissue at leastpartially therebetween.

Some variations of the first and second devices may comprise one or moremagnetic components. Optionally, the first and second devices may alsocomprise a longitudinal lumen therethrough. The first and second devicesmay also comprise one or more temperature sensors. In certainvariations, the first and second devices may have a first deliveryconfiguration and a second deployed configuration, where the devices arecompressed in the delivery configuration and expanded in the deployedconfiguration.

The first and second devices may each comprise one or more pre-shapedcurves in the second deployed configuration. In some variations, thepre-shaped curves may have varying radii of curvature, and/or may bespiral or funnel shaped. In some devices, the deployed configuration maycomprise one or more curves in one or more planes, and may comprise aring-structure coupled to an expandable net.

The tissue-affecting elements of the devices may affect tissue to form alesion using any suitable mechanism. For example, the tissue-affectingelements may ablate tissue using cryogenic substances, high intensityfocused ultrasound (HIFU), radiofrequency (RF) energy, lasers, heat,microwaves, and the like. Some tissue-affecting elements may ablatetissue using a combination of different mechanisms, as suitable for thetarget tissue.

Methods of affecting tissue in a body are also described. One variationof a method comprises advancing and positioning a first tissue-affectingdevice to a first surface of a target tissue, advancing and positioninga second tissue-affecting device to a second surface of a target tissue,where the second surface is opposite the first surface, positioning thefirst and second tissue-affecting devices so that ablation energy maypass between them, and operating both devices simultaneously to form alesion in the target tissue. In some variations, advancing the firstdevice may comprise inserting a curved sheath at a location beneath asternum and advancing the first device through the sheath. Optionally,the method may comprise withdrawing the first and secondtissue-affecting devices after the lesion is formed, as well asverifying and assessing the lesion using fluoroscopic, electricalimpedance, and thermal imaging techniques. In some variations of themethod, the tissue-affecting devices may comprise magnetic components.Tissue-affecting devices may apply a variety of ablation energies, forexample, cryogenic, high intensity focused ultrasound, laser energy,radiofrequency energy, heat energy and/or microwave energy. Thesemethods may be used to ablate tissue of the left atrium as part of aprocedure to treat atrial fibrillation, but may also be used to targetgastrointestinal tissue, as well as cancerous cell masses.

Methods of forming a lesion in the tissue of a left atrium are alsodescribed here. One variation of a method may comprise advancing andpositioning a first tissue-affecting device in the left atrium through apuncture or access site in a left atrial appendage, advancing a secondtissue-affecting device to an external wall of the left atrium, wherethe second device is positioned opposite to the first device, operatingboth devices simultaneously to form a lesion in the atrial wall betweenthem, and isolating the left atrial appendage. Optionally, the methodmay also comprise positioning the first and second devices with respectto each other using one or more magnetic components, and verifying andassessing the lesion using various imaging techniques (e.g.fluouroscopic, electrical impedance, and thermal imaging techniques). Insome variations, the first tissue-affecting device may be advanced overa first guide (e.g., guide wire) into the left atrium to circumscribethe base of a pulmonary vein, and the second tissue-affecting device maybe advanced over a second guide (e.g., guide wire) to circumscribe thetrunk of the pulmonary vein on the external atrial wall. Additionally oralternatively, the first guide wire and the first tissue-affectingdevice may be advanced into the left atrium to circumscribe the bases oftwo or more pulmonary veins, while the second guide wire and the secondtissue-affecting device may be advanced over the external atrial wall tocircumscribe the trunks of two or more pulmonary veins. In somevariations, isolating the left atrial appendage may comprise positioningan occlusion device comprising a rounded disc with one or more groovescircumscribing the outer perimeter of the disc, wherein the disc issized and shaped to be constrained in an ostium or base of the leftatrial appendage.

Also described here are kits for affecting tissue within a body. Onevariation of a kit may comprise a first device with one or moretissue-affecting elements and a longitudinal lumen therethrough, wherethe first device has a first compressed configuration and a secondexpanded configuration, a second device with one or moretissue-affecting elements and a longitudinal lumen therethrough, wherethe first and second devices are configured to operate simultaneously toform a lesion that spans at least a portion of tissue between them. Insome variations, the kit optionally comprises first and second devicesas described above, where the first and second devices also comprise oneor more magnetic components and/or one or more temperature sensors. Incertain variations, the kit may also comprise a closure member with anelongate body and a distal snare, where the elongate body may comprise alongitudinal lumen therethrough, a piercing member that is configured tobe advanced through the lumen of the elongate body, a first and secondcannula, and a first and second guide wire.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a heart with a partial cutaway in the left atrium.

FIG. 2 depicts one variation of a closure device.

FIG. 3A depicts an exploded view of one variation of an access device.FIG. 3B depicts one variation of an assembled access device.

FIG. 4 depicts one variation of an endocardial ablation device.

FIG. 5 depicts one variation of an epicardial ablation device.

FIGS. 6A-6F depict side and front views of different ablation arraysthat may be used with various ablation devices, including the devicesshown in FIGS. 4 and 5. FIGS. 6G and 6H depict variations of ablationarrays comprising temperature sensors. FIG. 61 depicts a partial cutawayof one variation of a temperature sensor that may be encapsulated in analignment magnet of an ablation array.

FIG. 7 depicts one variation of an occlusion device comprising anexpandable element.

FIG. 8A depicts a flowchart that represents one variation of a methodfor ablating cardiac tissue from both the endocardial surface andepicardial surface. FIG. 8B depicts a flowchart that represents anothervariation of a method for ablating cardiac tissue from both theendocardial and epicardial surface.

FIGS. 9A-9D depict ablation patterns that may be formed by endocardialand epicardial ablation of atrial wall tissue. FIGS. 9E-9G depictvariations of epicardial and endocardial ablation arrays that comprisetemperature sensor in various configurations.

FIGS. 10A-10S depict one example of an ablation method for ablatingtissue around the pulmonary veins, and for closing, and/or occluding,and/or removing the left atrial appendage. FIG. 10A schematicallyillustrates potential access sites to the pericardial space. FIGS.10B-10G schematically illustrate the use of a closure device to locateand secure the left atrial appendage. FIGS. 10H-10L schematicallyillustrate the positioning of endocardial and epicardial ablationdevices. FIGS. 10M-10N depict the alignment of endocardial andepicardial arrays using magnetic components. FIGS. 10O-10Q depictexamples of ablation profiles that may form lesions that electricallyisolate the tissue at or around or within the pulmonary veins. FIGS.10R-10S schematically illustrate the use of an occlusion device toocclude and isolate the left atrial appendage.

FIGS. 11A-11C depict one variation of a clip that may be used to securethe base or ostium of an atrial appendage.

FIGS. 12A and 12B depict various mechanisms by which an atrial appendagemay be occluded.

FIG. 13A depicts a flowchart that represents one variation of a methodfor ablating atrial wall tissue from an endocardial surface. FIG. 13Bdepicts a flowchart that represents another variation of a method forablating tissue from an endocardial surface.

FIGS. 14A and 14B depict ablation patterns that may be formed byendocardial ablation of atrial wall tissue.

FIG. 15 depicts a flowchart that represents one variation of a methodfor ablating atrial wall tissue from an epicardial surface, comprising aprocedure to close, and/or occlude, and/or remove the left atrialappendage.

FIGS. 16A and 16B depict ablation patterns that may be formed byepicardial ablation of atrial wall tissue.

FIG. 17A depicts one variation of an access device. FIG. 17B depicts across-sectional view of the access device of FIG. 17A taken along thelines 17B-17B. FIG. 17C depicts one variation of a curved region of thedevice of FIG. 17A with a plurality of slots. FIG. 17D depicts oneexample of how the access device of FIG. 17A may be used to provide anaccess path to the heart.

FIGS. 18A and 18B depict one variation of an occlusion device that maybe used to position a closure element around a left atrial appendage.

FIGS. 19A-19F another example of devices and methods that may be used toplace a device at or around a tissue structure.

DETAILED DESCRIPTION

The system and methods described herein may be used to affect anyportion of tissue within a body to form a lesion, and/or otherwiseelectrically isolate a portion of tissue. For illustrative purposes,these devices and methods are described in the context of lesionformation in the tissue of the left atrium for the treatment of atrialfibrillation, and may include the closure of the left atrial appendage.For example, methods for affecting tissue to treat atrial fibrillationmay comprise accessing the pericardial space of the heart, creating anaccess site through the left atrial appendage (LAA), advancing atissue-affecting device intravascularly and/or through the LAA tocontact an endocardial surface of the left atrium, advancing anothertissue-affecting device via the pericardial space to contact anepicardial surface of the heart, and affecting tissue from either orboth the endocardial and epicardial surfaces. In some variations, a LAAaccess/exclusion device may be used to stabilize the LAA for theadvancement of devices therethrough, as well maintain hemostasis byclosing and/or opening the LAA during and/or at the conclusion of theprocedure. While the systems and methods disclosed here are described inthe context of affecting cardiac tissue, it should be understood thatthese devices and methods may be used to affect a variety of tissues,such as the skin, heart, liver, etc., as well as to treat a variety ofconditions, including various cardiac deficiencies, tumors,gastrointestinal deficiencies, etc.

I. Anatomy

FIG. 1 depicts a heart (100), with the cavity of the left atriumpartially cut away to reveal a portion of the mitral valve (102) andpulmonary veins (104 a), (104 b), (104 c), (104 d). Both the rightatrial appendage (106) and the left atrial appendage (108) are shown,located on the superior portion of the heart (100). The heart (100) isenclosed by a pericardium (not shown), which is filled with a fluid thatmay separate it from the heart. The fluid-filled space between thepericardium and the heart is the pericardial space. In a heart affectedby atrial fibrillation, tissues associated with one or more of theseanatomical structures may pulsate irregularly or asynchronously, and maycause the atrium to contract quickly and/or irregularly. Procedures forthe treatment of atrial fibrillation may comprise the electricalisolation of arrhythmic cardiac tissue from other tissue regions. Insome variations, devices and methods for treating atrial fibrillationmay be directed towards the formation of lesions in the right atrium(e.g. in the proximity of the tricuspid valve annulus, the anteriorlimbus of the fossa ovalis, and/or the right atrial appendage), and/orlesions in the left atrium (e.g. in proximity of the pulmonary veinsand/or LAA). For example, one variation of a method for treating atrialfibrillation in the left atrium may comprise the electrical isolation oftissue(s) at or around or within each of the pulmonary veins, and mayoptionally include the closure, occlusion, and/or removal of the leftatrial appendage. While the devices and methods described below may beused to access, affect, and electrically isolate tissue in the leftatrium, similar devices and methods may be used to treat any suitableportion(s) of the heart, e.g., the right atrium, right ventricle, leftventricle, etc.

II. Devices Pericardial Access Device

In order to access certain portions of the heart, it may be useful toplace one or guide elements in the pericardial space around the heart.Various devices may be used to provide access to the pericardial spacefor the placement of a guide element into the pericardial space for theadvancement of subsequent devices to the heart. Some pericardial accessdevices may be configured to provide an access pathway from an initialaccess site (e.g., a sub-thoracic region, an intercostal region, etc.).For example, a pericardial access device may comprise a sheath with oneor more curves, and one or more needles, guide elements, tissue-piercingelements, etc. to create a pathway through the pericardium to access thepericardial space. In some variations, the one or more needles, guideelements, tissue-piercing elements, etc. may be sized and shaped tocorrespond with the one or more curves in the sheath. One example of asheath with one or more curves is shown in FIGS. 17A and 17B. As shownthere, the sheath (1702) may have a curved region (1706) between theproximal portion (1704) to the distal portion (1708). The proximalportion (1704) may be connected to a proximal sheath actuator. A sheathactuator may be used to advance the sheath, e.g., along a longitudinalaxis, to navigate the distal portion of the sheath, and/or may beconfigured to cause the curved region (1706) to bend. A cross-section ofthe sheath (1702) is depicted in FIG. 17B. The sheath (1702) may haveone or more longitudinal lumens therethrough, for example, a wire lumen(1710) and an access device lumen (1712). Other variations of a curvedor bendable sheath may have any desired number of lumens therethrough,e.g. 2, 3, 5, 8, etc. The wire lumen (1710) may be sized and shaped forpassing a wire therethrough. The access lumen (1712) may be sized andshaped to pass a pericardial access device therethrough, for example,any of the access devices described above. In some variations, sheathsmay have additional lumens for inserting other devices therethrough,and/or as necessary for accommodating mechanisms that may be used tocontrol the flexion of the curved region (1706).

The curved region (1706) may have one or more pre-shaped curves, and/ormay be flexible or bendable using a suitable actuating mechanismcontrolled by the sheath actuator at the proximal portion (1704). Thecurved region (1706) may serve to generally orient the sheath toward theheart upon insertion at an initial access point beneath the sternum,and/or may have a particular radius of curvature to help guide thesheath under the rib cage to the heart. In some variations, thecurvature of the curved region (1706) may be locked or fixed, e.g., thecurved region (1706) is first actuated to attain a desired degree ofcurvature, then locked to retain that desired curvature. Suitablelocking mechanisms may include, for example, maintaining the tension ofa wire that may be inserted through the wire lumen (1710), orimmobilizing the hinge mechanisms to a desired configuration. A flexibleor soft curved region may be locked into position by fixing theconfiguration (e.g., curvature, tension, etc.) of the wire within thewire lumen (1710). Some variations of a sheath may have a pre-shapedcurve, where the radius of curvature is determined at the time ofmanufacture, and remains unchanged as the sheath is used. The radius ofcurvature of the curved region may be adjusted for sheaths that areinserted at different initial access points. For example, the radius ofcurvature of a curved region of a sheath to be inserted at anintercostal access site may be different from the radius of curvature ofa curved region of a sheath to be inserted at a sub-thoracic accesssite.

The curved region (1706) may be made of a flexible or bendable material,or may be made of a substantially rigid material arranged inarticulating segments that allow for the curved region (1706) to bendwhen actuated. The curved region (1706) may be integrally formed withthe body of the sheath (1702), or may be separately formed and attachedto the sheath (1702). For example, the curved region (1706) may be madeof polymeric tubing and/or materials such as Pebax®, nylon,fluoropolymers (e.g., PTFE, FEP), polyethelene, Teflon®, polyethyleneterephthalate (PET), Tecothane®, etc. In some variations, the curvedregion (806) may be made of a polymeric tube with reinforced stainlesssteel or nitinol. Where the curved region (1706) is made of asubstantially rigid material, for example, stainless steel, nickeltitanium, nitinol, cobalt alloys (e.g. nickel-cobalt,cobalt-nickel-chromium-molybdenum), and/or polymers such as PEEK,polyethylene (HDPE), polyimide, etc., the curved region may be slottedor segmented to allow bending to occur. In some variations, a curvedregion (1707) may have one or more slots (1705), as illustrated in FIG.17C. In other variations, the curved region (1706) may comprise aplurality of segments, where the positioning of the segments withrespect to each other is controlled by a wire or pivot mandrel. Thesegments may be coupled together via mechanical hinges and/or livinghinges. Sheaths may also comprise multiple curved regions, where each ofthe curved regions may have the same or different radii of curvature.For example, one curved region may be made of a material with a selectedflexibility, while another curved region may be made of a material witha different flexibility. Other curved regions may be slotted orsegmented, as appropriate. Different curved regions may be separated bya straight portion of the sheath, or may be contiguous. A plurality ofcurved regions may help to provide additional maneuverability tonavigate the distal portion of the sheath to the targeted region of theheart. Adjusting the tension on a wire through the wire lumen (1710) mayalter the curvature of the curved region (1706). For example, increasingthe wire tension may cause bending of the curved region (1706), whiledecreasing the wire tension may cause straightening of the curved region(1706).

FIG. 17D depicts one variation of a method of using the sheath (1702).The sheath (1702) may be inserted into the subject (1730) at a locationbeneath the sternum (1722). Prior to insertion, the sheath may besubstantially straight, or may be curved, as appropriate. Once thesheath (1702) has been inserted, the curved region (1706) may beadjusted in order to bring the distal portion (1708) close to thesurface of the heart (1720). For example, the distal portion (1708) maybe navigated underneath the ribs (1728) towards the heart (1720). Oncethe distal portion (1708) of the sheath (1702) is in a desired location,e.g., an anterior and/or slightly lateral side of the heart, the curvedregion (1706) may be locked to retain the curvature of the curvedregion. The location of the distal portion (1708) may be monitored usingany suitable imaging modality, for example, ultrasound, fluoroscopy, andthe like. In some methods, the location of the distal portion (1708) maybe monitored by tactile feedback.

An articulating sheath such as is shown and described above may beuseful for accessing the heart (1720) where the abdomen (1724) of thesubject (1730) may limit the angle at which the sheath (1702) may bepositioned. Certain subject anatomy, such as a smaller abdomen (1724)may provide a large range of maneuverability for the sheath (1702),while a larger abdomen (1724) may limit the range of maneuverability forthe sheath. Providing one or more curved regions may allow the heart tobe more readily accessed where subject anatomy limits the range in whichthe sheath may be positioned. For example, providing one or more curvedregions may help to reduce the force that may be required to positionthe sheath (1702), and may provide additional access paths to the heartin the event the originally planned pathway becomes unavailable.

Closure Device

Some methods for treating atrial fibrillation may comprise accessing anendocardial surface of the left atrium through the LAA via thepericardial space. Methods that utilize the LAA as an entry port mayalso comprise closing and/or opening the LAA during the procedure (e.g.,to advance devices therethrough) to maintain hemostasis. Optionally,methods may also comprise excluding the LAA at the conclusion of theprocedure. Such a device may be used during the procedure to stabilizethe LAA so that tissue-affecting devices may be advanced through the LAAinto the left atrium, and may be used to at the conclusion of theprocedure to permanently close off or otherwise occlude the LAA. Oneexample of a device that may be capable of locating, securing,manipulating, stabilizing, closing and/or excluding the LAA is depictedin FIG. 2. Closure device (200) may comprise an elongate body (202), ahandle portion (204) located at a proximal portion of the elongate body(202), an extension (205) located at a distal portion of the elongatebody (202), and a distal looped closure assembly (206) distally coupledto the extension (205). While the closure device disclosed below isdescribed in the context of locating, securing, manipulating,stabilizing and/or closing the LAA, it should be understood that theclosure device may be used to act on any desirable tissue.

The elongate body (202) may have any appropriate shape, for example, theelongate body may be substantially straight (as depicted in FIG. 2), ormay have one or more pre-formed curves and shapes. The elongate body(202) may have a suitable cross-sectional diameter and longitudinallength to facilitate navigating the closure device (200) through thevasculature to contact the LAA (or other target tissue). The elongatebody (202) may be made of one or more flexible or rigid materials, asmay be suitable for navigating towards the target tissue. In somevariations, the elongate body may be steerable, and comprise steeringmechanisms (such as mandrels, articulating and/or living hinges, cables,etc.) that allow a user to steer the elongate body using the handleportion (204). For example, the elongate body may be made of a singleintegral flexible material with one or more steering mandrels embeddedin the side wall of the elongate body, such that bending the mandrel(s)would cause a corresponding deflection of the elongate body, which mayhelp steer the elongate body towards the target tissue. Alternatively oradditionally, the elongate body may be made of a plurality of segmentsthat may be connected by articulating and/or living hinges. Each of theplurality of segments may be rigid or flexible. One or more mandrels maybe coupled to each of the plurality of segments, and may be used to bendand steer the elongate body towards the target tissue. The elongate bodymay also comprise locking mechanisms so that after the elongate body issteered to a target location, it may be locked to retain a certainconfiguration to maintain contact with that target location. Theelongate body (202) may comprise one or more working channels (208) thatextend from the proximal portion of the elongate body (202) to thedistal portion of the elongate body. A variety of devices may beinserted through the working channel in order to manipulate a portion oftissue. Alternatively or additionally, the closure device (200) may beadvanced over a guide element using the working channel (208).

As depicted in FIG. 2, the distal extension (205) may extend distallybeyond the distal end of the elongate body (202). This may allow foradditional working space as may be suitable for accessing the LAA. Forexample, the distal extension (205) may extend distally beyond thedistal-most portion of the working channel (208) of the elongate body.The length of the distal extension (205) may be selected such that whenthe base of the LAA is engaged by the distal looped closure assembly(206), the tip of the LAA may be close to (e.g., in contact with) thedistal-most portion of the working channel (208). This may allow devicesthat are advanced through the working channel (208) to directly contactand/or manipulate the tip of the LAA once it exits the working channel.

The distal extension (205) may be integrally formed with elongate body(202), or separately formed and attached to the elongate body (e.g., bywelding, melding, brazing, adhesives, etc.). The distal extension (205)may be made of rigid and/or flexible materials, and may be made of thesame or different materials as the elongate body. The elongate bodyand/or distal extension may be made of polymeric materials such asPebax®, polyethelyne, and/or other thermoplastic materials with variousdurometers or densities, and/or any polymers that may be tapered orgraduated for varying degrees of flexibility. Additionally oralternatively, the elongate body and/or distal extension may be made ofmetallic materials such as nitinol, stainless steel, etc. The loopedclosure assembly (206), distal extension (205), elongate body (202),and/or portions thereof may comprise visualization markers, such asfluorescent markers, echogenic markers, and/or radiopaque markers, thatpermit the closure device to be visualized using a variety of imagingmodalities. As with the elongate body (202) described above, the distalextension (205) may also be steerable. In some variations, the distalextension (205) may be steered independently from the elongate body,while in other variations, the distal extension (205) may be steeredtogether with the elongate body. For example, a steering mandrel thatmay be used to steer the elongate body may also be coupled to the distalextension so that the extension may be steered in concert with theelongate body. Alternatively, there may be a first mandrel for thesteering the elongate body and a second mandrel for steering the distalextension independently from the elongate body. Optionally, the distalextension may have one or more pre-shaped curves which may help tonavigate the closure device (200) to a target tissue region.

In some variations, the distal extension (205) may comprise one or morelumens that may extend from the distal-most end of the extension to theproximal portion of the closure device (e.g., to the handle portion). Alumen in the distal extension may slidably retain a portion of thelooped closure assembly such that the dimensions of the loop may beadjusted. For example, the lumen of the distal extension (205) mayslidably retain the looped closure assembly (206), which may comprise adistal loop (203). The distal loop (203) may comprise a snare loop and asuture loop that may be releasably coupled along the circumference ofthe snare loop. The distal loop (203) may be made of polymeric materialssuch as Pebax®, and/or metallic materials, such as nitinol, and/or anyelastic, malleable, deformable, flexible material. The portion of thedistal loop that extends outside of the extension, i.e., the externalportion of the distal loop, may be adjustable using an actuator at theproximal handle portion. Adjusting the length of the external portion ofthe distal loop (203) may help to snare and/or close, or release and/oropen, a LAA or any anatomical protrusion. While the distal loop (203)may have the shape of a circle, it may also have other shapes, e.g., anellipse, oval, triangle, quadrilateral, etc. In other variations, thelooped closure assembly may be configured (e.g. knotted, looped, coiled,etc.) for other functions, such as locating and securing tissue. Forexample, the looped closure assembly may optionally comprise tissuegraspers, hooks, or other such tissue engagement components that mayhelp secure and retain a tissue portion.

The looped closure assembly (206) may have an expanded (e.g., open)configuration, and a tightened (e.g., closed) configuration, where thecircumference of the loop in the tightened configuration is smaller thanin the expanded configuration. For example, a distal loop with anelliptical shape in the open configuration may have a length along theminor axis (e.g., the shortest dimension of the ellipse) from about 15mm to about 50 mm, e.g., about 20 mm, and a length along the major axis(e.g., the longest dimension of the ellipse) from about 15 mm to about50 mm, e.g., about 40 mm. A distal loop in the closed configuration mayhave a diameter equivalent to about 5 mm to about 10 mm, e.g., 6 mm. Thelooped closure assembly (206) may be tightened or cinched to encircleand secure the LAA, and in some variations, may be able to close the LAAafter it has been secured, if desirable. Optionally, the looped closureassembly (206) may be releasably coupled to the closure device such thatafter the LAA is encircled and secured by the distal loop (203), a knotor locking element may be deployed to retain the tension on the distalloop, which may then be released from the closure device. For example, alooped closure assembly may have a releasable suture loop that istightened over the LAA and then released from the closure device. Thetension on the suture loop may be locked so that the looped closureassembly may be proximally withdrawn from the suture loop. Optionalclosure elements, such as sutures, graspers, clips, staples, and thelike, may be included with the looped closure assembly to help close theLAA. For example, additional closure features, e.g., graspers orstaples, may be included at the tip of distal extension (205) that mayact to secure the LAA. A looped closure assembly may also comprise oneor more energy sources distributed along the length of the distal loop,where the energy sources may be used to ablate tissue or induce tissuefusion. Alternatively or additionally, the looped closure assembly (206)may be actuated in conjunction with other devices advanced through theworking channel (208) to secure and position the closure device withrespect to the LAA.

Various types of devices may be inserted through the working channel(208) of the elongate body (202) as may be desirable. In somevariations, a vacuum device may be inserted through working channel(208), while in other variations, alignment devices, guide elements,grasper devices, visualization devices, ablation devices, and/or cuttingdevices may be inserted through the working channel. Variations of theclosure device may have a multi-lumen elongate body, where each lumenmay be a working channel for one or more different devices. For example,the elongate body (202) may have multiple working channels for theinsertion of different devices. Additionally or alternatively, theelongate body (202) may comprise working channels for the injection ofliquid or gas fluids, as well as the application of therapeutic and/orchemical agents. The working channel (208) may have any cross-sectionalshape as may be suitable for the devices to be inserted therethrough,for example, circular, rectangular, etc.

The closure device (200) may comprise mechanisms to control the bendingand/or steering of the elongate body, as well as adjust the length ofthe distal loop that extends outside of the distal extension. Forexample, these functions may be controlled by levers and/or knobs at thehandle portion (204). The handle portion (204) may comprise a housing(214), a loop actuator (212), and a working channel actuator (210). Thehousing (214) may enclose at least a portion of the actuators thatcontrol the use of the elongate body, the looped closure assembly, andthe device in the working channel of the elongate body. For example,loop actuator (212) may regulate the tension on the distal loop of thelooped closure assembly, and control the circumference of the externalportion of the distal loop, e.g. decrease it to encircle and/or closethe LAA, and increase it to release the LAA. In some variations, theloop actuator (212) may be a slider configured to adjust thecircumference of the distal loop (203). In variations where the distalloop comprises a releasable suture loop, the loop actuator may alsocomprise a fob that initially couples the suture loop with the closuredevice and may be pulled to release the suture loop from the closuredevice. The working channel actuator (210) may comprise one or morebuttons, sliders, levers, knobs, and the like that are configuredregulate the operation of the device(s) in the working channel(s) ofelongate body (202). For instance, the working channel actuator (210)may be a grasper actuator, and/or vacuum actuator. Optionally, handleportion (204) may also comprise one or more buttons, sliders, levers,and/or knobs that may be used to navigate the LAA access device throughthe vasculature to access the LAA, for example, by rotating, pulling,pushing, bending, or otherwise manipulating steering mandrels. Otherfeatures of a closure device and methods of use are described in U.S.patent application Ser. No. 12/055,213 (published as U.S. Pub. No.2008/0243183 A1), which is hereby incorporated by reference in itsentirety. Another example of a closure device and methods of use aredescribed in U.S. patent application Ser. No. 12/752,873, entitled“Tissue Ligation Devices and Controls Therefor,” filed Apr. 1, 2010,which is hereby incorporated by reference in its entirety.

LAA Access Device

As described above, a variety of devices with different functions may beinserted through the working channel(s) of the elongate body of aclosure device to secure and/or otherwise manipulate a portion oftissue. In procedures where access to an internal tissue structure maybe desired (e.g. accessing a lumen of a hollow organ or vessel), anaccess device may be inserted through the working channel of the closuredevice after the closure device has been advanced at or near the targettissue (e.g., by advancing the closure device over a guide element).Access devices may create a way for the internal portion of a tissue tobe accessed from outside the tissue. In some variations, access devicesmay create an incision, puncture, and/or opening, etc., which may bedilated to allow access to devices larger than the initial opening.Optionally, some variations of an access device may also comprise aguide wire that may be advanced into the created access site. Oneexample of such a device is shown in FIGS. 3A and 3B. FIG. 3A showsindividual components of one variation of an access device that may beused to access a LAA or other tissue, and FIG. 3B shows the accessdevice of FIG. 3A fully assembled. In this variation, LAA access device(300) comprises an access wire (302), a piercing wire (304), and anactuator portion (306). The access wire (302) may comprise a lumen (303)therethrough, where the lumen (303) may be sized and shaped for thepassage of a piercing element therethrough, e.g. the piercing wire(304). The access wire (302) may be made of a metal alloy or one or morepolymers that have mechanical properties suitable for threading the LAAaccess device (300) in the working lumen of a LAA stabilizing device andfor guiding the piercing element. The access wire (302) may be made of avariety of materials, including but not limited to nitinol, stainlesssteel, as well as polymeric materials such as polyethylene,polypropylene and the like. The piercing wire (304) may be threadedthrough the lumen (303) of the access wire (302), and may comprise apiercing tip (308) at the distal portion. The piercing tip (308) may beused to create a puncture through the LAA. Optionally, the piercing wire(304) may comprise a lumen therethrough for the insertion of otherdevices, such as a catheter, guide wire, suture, and/or may be used forthe infusion of fluids (e.g. gas or liquid fluids). In some variations,the piercing tip (308) may be a needle that is attached to the distalportion of the piercing wire (304). The piercing tip (308) may beseparately or integrally formed with the piercing wire (304), and mayhave a lumen therethrough. The proximal portion of piercing wire (304)may be coupled with the actuator portion (306). The actuator portion(306) may be used to advance and/or withdraw and/or steer and/or rotatethe piercing wire (304), and may also be used to maneuver the accesswire (302) to access the LAA or other target tissue. The actuatorportion (306) may be manual or mechanized, and may contain ergonomicfeatures as appropriate, as well as electrical/mechanical interfaces toreceive and execute instructions from a computing device ormicrocontroller. For example, the actuator portion (306) may be made ofa metal alloy and/or one or more polymers that may be shaped to have anergonomic geometry. The actuator portion (306) may be made of anymaterials that possess sufficient rigidity, flexibility, durability,etc., to engage and control the mechanisms driving the use of theclosure device (200).

Corresponding Ablation Devices

Another example of a device that may be advanced through the workingchannel(s) of the elongate body of a closure device is atissue-affecting device. Devices that affect tissue may generallycomprise one or more tissue-affecting elements, arranged in variouspatterns. In some variations, two or more tissue-affecting devices maybe positioned along a target tissue, and used to affect the tissue in adesired pattern, where the tissue-affecting elements may be operatedsimultaneously or sequentially. In some variations, the two or moretissue-affecting devices may be placed across each other on oppositesides of tissue such that the tissue between them is affected. Oneexample of a tissue-affecting device is an ablation device. Ablationdevices may be provided for procedures that aim to ablate a portion oftissue that is abnormal, for example, cancerous tissue, or arrhythmiccardiac tissue. While affecting tissue by ablation is described indetail here, tissue may be affected in other ways, including byexcision, occlusion, manipulation and the like. As described below, anablation device may be used to ablate fibrillating atrial tissue, whichmay help to prevent the conduction of the irregular or asynchronouspulses in one tissue region to another tissue region.

In some variations, ablation devices may be used to create a lesion inthe fibrillating atrial tissue. For the treatment of atrialfibrillation, one or more tissue-affecting devices, such as ablationdevices, may be positioned on the endocardial surface and/or theepicardial surface of the left atrium. One example of an endocardialablation device that may be inserted through a closure device is shownin FIG. 4. Endocardial ablation device (400) may comprise an elongatebody (402), a handle portion (404), one or more ablation source(s)(406), and an ablation array (408). The elongate body (402) may be sizedand shaped to be inserted through a working channel of a closure device,or any suitable guide cannula or sheath. The elongate body (402) maycomprise one or more lumens therethrough, where the lumens may beconfigured to pass devices or fluids from the proximal handle portion(404) to the ablation array (408) at the elongate body distal portion.The elongate body may have any number of pre-formed curves for ease ofnavigation to the target tissue, and may optionally be flexible and/orsteerable. While the elongate body (402) may be one continuous segment,other variations of an elongate body may be made of multiplearticulating segments, and may be made of one or more flexible and/orrigid materials. In some variations, the elongate body may be steerablevia a mechanism in handle portion (404), and as previously described forthe closure device. In variations where the elongate body is passedthrough a portion of a closure device, the curvature and steerability ofthe elongate body (402) may correspond to the curvature and steerabilityof the closure device. This may help to inform a practitioner of theorientation of the endocardial ablation device with respect to theorientation of the closure device.

As shown in FIG. 4, the ablation array (408) may be located at thedistal portion of elongate body (402). An ablation array may compriseone or more tissue-affecting elements that may be used for ablatingand/or otherwise forming a lesion in tissue. For example, the ablationarray (408) may comprise magnets (410) and ablation elements (412) thatmay be arranged, for example, along pre-formed curves or loops of theablation array (408). The elongate body may also comprise magnets. Themagnets may be of any suitable type. For example, the magnets may berare-earth, electro-activated, or a multi-alloy (e.g. iron, boron,neodymium) magnets. The magnets may also have any suitable size orshape. More generally, the distal portion of an elongate body may haveany open-shape or closed-shape geometry, and the magnetic and/orablation elements may be arranged along the elongate body, ablationarray, and/or on a structure at least partially enclosed within theperimeter of a shaped distal portion of the elongate body. In somevariations, the ablation elements may themselves be magnetic. There maybe any number of magnets (410) having any suitable configuration(s) orpattern(s), placed at any suitable location on the ablation array. Forexample, the magnets (410) may be arranged in a straight or curved linealong the curvature of the ablation array (408), as shown in FIG. 4.Magnets may also be arranged along a length and a width of ablationarray. There may be any number of ablation elements (412) as may besuitable to help ensure that sufficient ablation coverage of the targetarea is provided. For example, there may be 1, 2, 3, 5, 10, 12, 20, etc.ablation elements. In general, ablation elements may be utilize anymechanism and be in any form that conveys the ablation energy/medium tothe target tissue. For example, cryo-ablation elements may compriseconduits that may circulate a cryogenic substance in conductiveproximity to the target tissue. Ablation elements may be electrodes thatablate tissue via radiation or heat energy. Alternatively oradditionally, ablation elements may be outlets or ports that infusesubstances that cause necrosis or apoptosis. For example, ablationelements may ablate tissue using one or more methods, such ascryo-ablation, heat ablation, high intensity focused ultrasound (HIFU)ablation, radiofrequency (RF) ablation, laser ablation, or combinationsof the listed methods and/or any method that causes necrotic orapoptotic cell and/or tissue death. Some ablation arrays may comprisetwo or more different types of ablation elements, e.g., 2, 3, or 4 typesof ablation elements. In some variations, an ablation array may compriseboth RF and cryo-ablation elements. In some variations, an ablationarray may comprise RF electrodes and HIFU electrodes. In still othervariations, an ablation array may comprise laser emitters and RFelectrodes. In some variations, an ablation array may comprise HIFUelectrodes, RF electrodes, and cryo-ablation elements. The differenttypes of ablation elements on an ablation array may be activatedsimultaneously and/or sequentially in the course of ablating tissue.Alternatively or additionally, ablation elements may be sharp elements,e.g. needles, that excise, cut, or pierce tissue, or any combination ofthe above. For example, an endocardial ablation device may compriseelectrode ablation elements and needle ablation elements.

The shape of the ablation array (408) as shown in FIG. 4 issemi-circular, which may be suitable for circumscribing and ablatingaround a vascular structure, such as a pulmonary vein, however, othervariations of ablation arrays may have other shapes. For example, anablation array may have a planar structure with a length and a width,with ablation elements arranged along both the length and the width. Anablation array may also be a one-dimensional array, e.g., a linearstructure, where the ablation elements are arranged linearly therealong.Indeed, ablation arrays may be any shape suitable for accessing andcontacting the target tissue. For example, the semi-circular shape ofablation array (408) may be suited for circumscribing vascularstructures, such as veins or arteries, and may be configured to createcircular ablation patterns. Ablation arrays may also have a taperedregion that may be helpful in accessing and contacting in the lumen oftubular structures, e.g., the inner lumen of a vein. In some variations,an ablation array may have a narrow undeployed configuration and anexpanded deployed configuration. For example, an ablation array may beconstrained in a sheath for delivery, and may expand into the deployedconfiguration by removing the sheath. In another variation, a curvedablation array may be retained in a straight configuration by astraightening mandrel for delivery, and may be expanded into the curveddeployed configuration by removing the mandrel. Other variations will bedescribed in detail below.

The ablation array (408) may be made from a flexible or shape-memorymaterial, such that it may be advanced to the target tissue in asubstantially straight configuration, and may be deployed and contactedto tissue in a curved configuration. In some variations, the ablationarray is made of a different material from the remainder of the ablationdevice (400), and may have different mechanical properties. For example,the proximal portion (405) of the elongate body may be made of a firstmaterial, while the distal portion (407) and/or the ablation array maybe made of a second material. Examples of materials that may be suitablefor the proximal portion (405) and/or the distal portion (407) of theelongate body may include metal alloys such as nickel titanium alloy,stainless steel, and/or any polymers, such as polyethylene,polyurethane, polypropylene, polytetrafluoroethylene, polyimide, etc.,and/or any combinations thereof. In some variations, an ablation arraymay be integrally formed with the proximal portion of the ablationdevice, or may be attached via an articulating hinge. The ablation arraymay also be attached by other mechanical mechanisms, such as a livinghinge, pivot joint, ball joint, etc, which may allow the ablation arrayto move with respect to the proximal portion of the ablation device(e.g., with two or more degrees of freedom).

The handle portion (404) located at the proximal end of elongate bodymay comprise actuating elements that control the movement and/or actionof the elongate body and ablation array. In some variations whereendocardial ablation device (400) is manually operated, the handle (400)may be ergonomic, while in other variations where the device ismechanically/electrically operated, handle (400) may comprise aninterface to receive and execute instructions from a computing device.The handle portion (404) may comprise an ablation array actuator (414),which may be used to regulate application of ablation energy/substancesto the ablation array to the target tissue (e.g. frequency, duty cycle,magnitude/amplitude, etc.). Additionally, the handle portion (404) maycomprise an actuating mechanism that controls the movement (e.g.,bending, flexing, etc.) and position of elongate body (402). The handleportion (404) may also comprise an interface to the ablation source(s)(406), and provide a conduit or conduction pathway from the ablationsource(s) (406) to the ablation array. For example, the ablation source(406) may comprise a reservoir of cryogenic substances (e.g., forcryo-ablation), which may be transported through a lumen in the elongatebody (402) to the ablation array. Alternatively or additionally, theablation source (406) may comprise a source of radioactive substances(e.g., radioactive seeds or fluids), and/or a light beam source (e.g.,for laser ablation), and/or an ultrasound source (e.g., for HIFUablation), and/or a radiofrequency source, and the like, which may bedelivered or transmitted from the handle portion to the ablation array.In some variations, different ablation sources may be used together inthe same ablation device.

Depending on the tissue to be ablated and the desired ablation pattern(e.g. lesion geometry and size) desired, a second ablation device may beprovided, where the second ablation device corresponds to the firstablation device. A second ablation device may increase the tissueablation area and/or may otherwise alter the ablation characteristics ofthe first ablation device (e.g. by constructive or destructiveinterference). For the purposes of ablating tissue of a left atrium, asecond ablation device may be provided to help ensure that the lesionformed by ablating tissue spans at least portion of tissue that isbetween them. In the treatment of atrial fibrillation it may bedesirable to electrically isolate the fibrillating tissue from othertissues. In some variations, the formation of a lesion that spans theentire thickness of the atrial wall (e.g., from the endocardial surfaceto the epicardial surface) using one or more ablation devices mayimprove the electrical isolation of a portion of the atrial wall fromother portions of the heart. Accordingly, in some variations, ablationdevices may be placed on opposite sides of a tissue wall such that alesion that spans a substantial portion of the tissue wall between theablation devices may be formed. In some variations, positioning a firstablation device on an interior wall (endocardial surface) of the leftatrium, and positioning a second ablation device on an exterior wall(epicardial surface) of the left atrium opposite to the first ablationdevice, may help form a lesion that spans at least a portion of thetissue between the first and second ablation devices. FIG. 5 illustratesone variation of an epicardial ablation device (500) that may be usedwith an endocardial ablation device to form a lesion in the left atrium.The epicardial ablation device (500) may comprise an elongate body(502), handle portion (504), ablation source (506), and an ablationarray (508). As shown in FIG. 5, the ablation array (508) may be locatedat the distal portion of elongate body (502). The ablation array (508)may comprise magnets (510) and ablation elements (512) which maycorrespond to the magnets (410) and ablation elements (412) of theendocardial ablation device (400). The magnets of the epicardial andendocardial ablation devices attract each other when the ablation arraysare placed on opposite sides of tissue, which may act to align theepicardial and endocardial ablation devices. For example, the magnets(510) may be positioned on the epicardial ablation array (508) such thatthey may be aligned with the magnets (410) of the endocardial ablationarray (408), e.g. magnets (510) may correspond to, or be mirror imagesof magnets (410). As with the magnets, the ablation elements (512) maycorrespond to, or be mirror images of the ablation elements (412), orthey may be interlaced between the ablation elements (412). In somevariations, the alignment and attraction of the magnets may position theendocardial and epicardial ablation devices such that the ablationelements of the ablation devices are aligned across from each other. Theshape of the ablation array (508) as shown in FIG. 5 is semi-circular,however, other variations of ablation arrays may have any shape as maybe suitable for accessing and contacting the target tissue. In somevariations, the shape of ablation array (508) may be a mirror image, orcomplementary image, of the endocardial ablation array (408). Forexample, the semi-circular shape of the ablation array (508) may besuited for circumscribing vascular structures, such as veins orarteries. Other variations will be described in detail below. Theablation array (508) may be made from a flexible or shape-memorymaterial, such that it may be advanced to the target tissue in asubstantially straight configuration, and may be deployed and contactedto tissue in a curved configuration. For example, ablation array may beadvanced to, and contacted with, an external wall of a vascularstructure, e.g. artery, vein, heart chamber, and/or atrial appendage.The ablation elements of the endocardial array and the epicardial arraymay be in communication with each other, so that they may apply ablationenergy in a concerted or programmed fashion.

The handle portion (504) located at the proximal end of elongate bodymay comprise actuating elements that control the movement and/or actionof the elongate body and ablation array. In some variations where theendocardial ablation device (500) is manually operated, the handle (500)may be ergonomic, while in other variations where the device ismechanically/electrically operated, the handle (500) may comprise aninterface to receive and execute instructions from a computing device.The handle portion (504) may comprise an ablation array actuator (514),which may be used to regulate application of ablation energy/substancesto the ablation array to the target tissue (e.g. frequency, duty cycle,magnitude/amplitude, etc.). In some variations, the handle portion (504)may be in communication with the handle portion (404) of the endocardialablation device (400), such that ablation energy from both ablationdevices may be applied in-phase or out-of-phase to form a desiredablation wavefront and/or profile. Additionally, the handle portion(504) may comprise an actuating mechanism that controls the movement andposition of elongate body (502). The handle portion (504) may alsocomprise an interface to ablation source(s) (506), and provide a conduitor conduction pathway from the ablation source(s) (506) to the ablationarray. For example, the ablation source (506) may comprise a reservoirof cryogenic substances (e.g., for cryo-ablation), which may betransported through a lumen in the elongate body (502) to the ablationarray. Alternatively or additionally, the ablation source (506) maycomprise a source of radioactive substances (e.g., radioactive seeds orfluids), and/or a light beam source (e.g., for laser ablation), and/oran ultrasound source (e.g., for HIFU' ablation), and/or a radiofrequencysource, and the like, which may be delivered or transmitted from thehandle portion to the ablation array. In some variations, differentablation sources may be used together in the same ablation device.

Variations of Ablation Arrays

While the ablation devices depicted and described in FIGS. 4 and 5 areshown as having a semi-circular shape, ablation arrays may have othergeometries. Ablation and/or other tissue-affecting arrays may have avariety of geometries and sizes as appropriate to accommodate andcontact the target anatomical structure. For instance, ablation arrayswith various geometries may be suitable for contacting and ablatingtissue, especially vascular or cardiac tissue. Several variations ofablation arrays are shown in FIGS. 6A-6F. A side view and front view ofa spiral ablation array (600) inserted in the opening of a vascularstructure (603) (e.g. pulmonary vein) is shown in FIGS. 6A and 6B,respectively. As shown there, the spiral ablation array (600) may becoupled to the distal portion of an elongate body (602), where ablationelements (604) and magnetic elements (606) are arranged throughout thecurves of the array (600) such that they may contact the walls of thevascular structure (603). FIGS. 6C and 6D depict a side view and a frontview of a woven ablation array (610), respectively. The ablation array(610) may be attached at the distal portion of an elongate body (612),and may comprise a woven portion (615) and a rim (617) located along adistal perimeter edge of the woven portion. Ablation elements (614)and/or magnetic elements (616) may be arranged throughout the array, forexample, along the rim (617) and/or on various locations on the wovenportion (615). The size and shape of the woven portion (615) may beconfigured to position the ablation elements (614) and the magneticelements (616) in order to accommodate the geometry of the target tissue(613), e.g., where the expanded size and shape of the woven portion maybe bent, shaped, molded or otherwise constrained by the geometry of thetarget tissue. The woven portion (615) may be used as an ablationconduit or array, and may be arranged to be in proximity to targetablation tissue. Alternatively or additionally, the woven portion (615)may help stabilize the array (610) during ablation without occluding thepulmonary vein. The woven portion (615) may be constructed from variousfibers, where the density of the weave may be adjusted according to thedegree of perfusion desired. The fibers of the woven portion may be madeof polypropylene, polyurethane, polyethylene, polytetrafluoroethylene,as well as metal alloys such as stainless steel and/or nickel titaniumalloy. The woven portion may be self-expanding or mechanically expandedto fill the lumen or orifice of the vascular structure, and may beadjusted according to the size of the vascular structure. In somevariations, the woven portion may be made of a shape-memory material sothat the woven array (610) may have a compressed delivery configurationand an expanded deployed configuration. The size of the woven portionmay be adjusted to ablate anatomical structures with dimensions of about8.0 mm to about 30 mm, or about 12.0 mm to about 18.0 mm. Anothervariation of an ablation array (620) is shown in FIGS. 6E and 6F. Asshown there, a tapered spiral ablation array (620) may be coupled to thedistal portion of an elongate body (622), where ablation elements and/ormagnetic elements may be arranged throughout the tapered spiral ablationarray (620). The tapered spiral ablation array (620) may comprise asingle continuous flexible backbone that is wound around the elongatebody (622). Ablation elements may be distributed along the length of thebackbone. In some variations, the backbone of the spiral ablation array(620) may be a wire that is electrically conductive, and may itself becapable of ablating tissue without additional ablation elements. Thespiral ablation array (620) may have a first collapsed configurationshown in FIG. 6E, where the ablation array may be closely wound aroundthe distal portion of the elongate body (622), e.g., with a tight radiusof curvature. The narrow profile of the array in the collapsedconfiguration may help navigate the array atraumatically through narrowanatomical structures, and may also be inserted into folded or creasedtissue structures. The ablation array (620) may be retained in itscollapsed delivery configuration by a sheath that may be slidablydisposed over the array (not shown), and/or by retaining tension on thebackbone. FIG. 6F depicts a second expanded configuration of the taperedspiral ablation array (620), where removing the sheath and/or reducingthe tension on the backbone of the spiral ablation array (620) may allowthe backbone to loosen the radius of curvature such that the profile ofthe array expands. In some variations, expanding the ablation array mayact to dilate a narrow tissue structure, e.g., open a folded or creasedtissue structure, enlarge a tissue lumen or aperture for the insertionof additional devices, etc. In some variations, the ablation array (620)may help to maintain perfusion during ablation, and may be an alignmentreference point for epicardial elements at various locations along thepulmonary veins. The ablation and magnetic elements may be arranged inany of the previously described configurations, and may be arranged tohelp stabilize the ablation device during the ablation procedure.

Any of the ablation arrays described above may optionally comprise oneor more temperature sensors. Temperature sensors may be used to measurethe ablation energy that has been applied to a tissue, and may be usedto evaluate the degree to which tissue is ablated. The measurement oftemperature changes in the tissue during the application of ablationenergy may be used to regulate the duration, power, and/or frequency ofthe ablation energy (e.g., by providing feedback information to theablation array and/or ablation array controllers). Monitoring thetemperature of the tissue during ablation may also help preventexcessive or harmful damage to peripheral tissues. The one or moretemperature sensors may be thermocouples, thermsistors, thermalresistive sensors (RTD), and the like. One example of an ablation arraywith temperature sensors is depicted in FIG. 6G. Ablation array (630)may comprise an ablation array substrate or housing (634), one or moreablation elements (not shown), one or more alignment magnets (638) andone or more atraumatic temperature sensors (636) on the tissue-facingsurface of the ablation array. The alignment magnets (638), temperaturesensors (636), and ablation elements may be arranged in any suitableconfiguration on the tissue-facing surface of the ablation array, forexample, the alignment magnets (638) may be arranged such that theablation elements of two ablation arrays positioned on opposite sides ofa tissue may attract each other to align the ablation elements of oneablation array to the other. The atraumatic temperature sensors (636)may be pressed into the tissue (632) without puncturing or piercing itto measure the temperature of the tissue. Another example of an ablationarray with temperature sensors is depicted in FIG. 6H. Ablation array(640) may comprise an ablation array substrate or housing (644), one ormore ablation elements (not shown), one or more alignment magnets (648)and one or more sharp temperature sensors (646) on the tissue-facingsurface of the ablation array. The alignment magnets (648), temperaturesensors (646), and ablation elements may be arranged in any suitableconfiguration on the tissue-facing surface of the ablation array, aspreviously described. The sharp temperature sensors (646) may beinserted into tissue (642) to measure the temperature of the tissue at acertain depth from the surface of the tissue (642). In some variations,the sharp temperature sensors (646) may pierce or puncture the tissue(642) in order to gain access to deeper tissue regions. The sharptemperature sensors (646) may also have a length that corresponds to thethickness of the tissue, and in some cases, may penetrate through theentire length of the tissue. Temperature sensors that penetrate throughsubstantially the entire thickness of the tissue may provide temperaturedata across the entire span of the tissue, which may provide anindication of the uniformity of the tissue ablation, as well as provideinformation about the temperature gradient across the tissue. This mayhelp improve the accuracy of the tissue temperature measurement that isfed back to the ablation array and/or ablation array controllers.

In the variations depicted in FIGS. 6G and 6H, the alignment magnets andtemperature sensors are located adjacent to each other, however, inother variations, the alignment magnets and temperature sensors may beincorporated together in one location. This may help to reduce theoverall size of the ablation array, which may reduce the profile of thearray for ease of delivery to the target tissue site. For example, anablation array may have alignment magnets that have a lumen sized andshaped for encapsulating a temperature sensor. FIG. 61 depicts a regionsof one example of an ablation array (650) comprising a housing (654), atemperature sensor (656) and an alignment magnet (658) encapsulating thetemperature sensor. The alignment magnet (658) may comprise a lumen(657) that is sized and shaped for the temperature sensor (656). Thetemperature sensor (656) (which may be an atraumatic or tissue-piercingor sharp temperature sensor) may protrude from the lumen (657), or maybe flush with the opening of the lumen (657). In other variations, anablation array may comprise one or more ablation elements that eachcomprise a lumen such that a temperature sensor may be encapsulated inthe lumen. In still other variations, an ablation array may compriseablation elements, alignment magnets, and/or temperature sensors thatmay be retracted into a housing of the ablation array. For example,during delivery of the ablation array to the target tissue site, theablation elements, alignment magnets, and/or temperature sensors may bein a first retracted configuration, such that the profile of theablation array is narrow. After the ablation array has been generallypositioned at the target tissue site, the ablation elements, alignmentmagnets, and/or temperature sensors may be a second protractedconfiguration, where the ablation elements, alignment magnets, and/ortemperature sensors are capable of contacting the target tissue foralignment, ablation, and/or measurement of temperature.

Occlusion Device

As described previously, some methods may include steps to help maintainhemostasis in the course of the procedure for the treatment of atrialfibrillation. For example, in procedures where access to an endocardialsurface of the heart is gained using the LAA as a port, it may bedesirable to close and/or exclude the LAA to maintain hemostasis and/orhelp prevent thrombosis. In some variations, a procedure for thetreatment of atrial fibrillation may also include the temporary orpermanent closure, and/or occlusion, and/or removal of the left atrialappendage. FIG. 7 illustrates one variation of an occlusion device (700)that may be used with the devices and methods described here. Theocclusion device (700) may comprise an elongate body (702), an insertport (704) at a proximal portion of the elongate body, and an expandablemember (706) at a distal portion of the elongate body. The elongate body(702) may have one or more lumens, for example, a guide wire lumen (708)sized and shaped for passing a guide wire therethrough. The elongatebody (702) as shown in FIG. 7 may also comprise one or more sideapertures (710) and imaging markers (712). Any number of side apertures(710) may be provided for infusion of any fluid substance, such as acontrast agent or pharmacological agent (e.g., heparin, antibacterialagent, etc.). The imaging markers (712) may be radiopaque or echogenic,etc., as appropriate for the imaging modality used to monitor theposition of the occlusion device (700).

The elongate body (702) may be made from one or more rigid and/orflexible materials. In some variations, the elongate body (702) may besteerable. An insert port may comprise one or more apertures for theinsertion of fluids or devices through the elongate body (702). Forexample, the insert port (704) may comprise a guide wire aperture (714)and a fluid lumen (716). The guide wire aperture (714) and the fluidlumen (716) may each have independent lumens that may merge into onelumen at a bifurcation (717) of the insert port (704), or may each haveseparate lumens in the elongate body (702). The guide wire aperture(714) may be continuous with the guide wire lumen (708), and the fluidlumen (716) may be continuous with a cavity of the expandable member(706), such that the introduction of fluid into or out of the fluidlumen (716) may expand or constrict the expandable member. Optionally,the insert port (704) may also comprise actuation mechanisms fornavigating and adjusting the shape of the elongate body (702), as wellas control the motion of a guide wire, and the expansion of theexpandable member (706).

The expandable member (706) may be any structure that comprises a firstsmall profile and a second larger profile, for example, a balloon or anarticulating polygonal structure, e.g. rectangular prism or tetrahedron,and the like. The expandable member (706) may be sized and shaped to fitwithin the guide wire lumen (208) of the closure device (200) so that itmay be advanced and/or withdrawn through the lumen (208). In somevariations, the expandable element (706) may have a first collapsedconfiguration, and a second expanded configuration. For example, therounded expandable element (706) shown in FIG. 7 may have a diameter ofabout 15 mm to about 30 mm, e.g., 20 mm. The expandable member may bemade of various materials, including polymeric and/or metallicmaterials. Examples of polymers that may be used in an expandable membermay include materials such as latex, silicone, polyisoprene,polyethelene. Example of metals and/or metallic alloys that may be usedwith an expandable member may include nitinol, stainless steel, titaniumand the like. The expandable member may be configured to either selfexpand or be mechanically expanded by an actuator. For example, theexpandable member (706) may be transitioned from the small profile tothe larger profile by introducing positive pressure or by a mechanicalactuation. In some variations, a balloon expandable member may be urgedinto the larger configuration by applying positive fluid (gas or liquid)pressure into the lumen of the balloon. The expandable member may haveany shape and size as appropriate for the target tissue. For example, around expandable balloon may be used to occlude a vascular structure,such as a vein or an atrial appendage, e.g. LAA.

Another variation of a device that may be used for occluding the LAA isdepicted in FIGS. 18A and 18B. As shown there, an occlusion device(1820) may comprise grooves (1822) in its deployed configuration. Insome variations, the closure device may be deployed and positioned atthe anatomical ostium of a left atrial appendage (1800). However, theocclusion device (1820) may be positioned at any desired location in theheart. The occlusion device (1820) may have a collapsed deliveryconfiguration, which may enable it to be enclosed within a catheter orsheath and advanced through the vasculature (e.g., from a retrogradeapproach, or an antegrade transseptal approach) or through a port in theLAA. The occlusion device (1820) may be deployed into its expandedconfiguration after it is positioned at or near the ostium of the LAA.In some variations, the occlusion device may be a rounded plate or disccomprising one or more grooves circumscribing the outer perimeter.Grooves (1822) may be configured to interfit with a closure element(1810) (e.g., suture loop or snare loop) of a closure device as thecircumference of the closure element is reduced, as shown in FIG. 18B.The occlusion device (1820) may be sized according to the desired degreeof closure of the left atrial appendage (1800). Once the closure element(1810) has been secured and decoupled from the rest of the closuredevice (e.g., by cutting or detaching at a breakaway point), theocclusion device (1820) may be reverted to its collapsed configurationand withdrawn from the ostium of the left atrial appendage (1800). Thedevices and methods described above for closing and/or excluding theleft atrial appendage may be included at the conclusion of a procedurethat uses the left atrial appendage as an access site. This may be amore expedient method of closing a heart access site than otherconventional methods, such as suture stitching, which may besubstantially more time-consuming.

The above-described devices may be used to secure, ablate, and excise aportion of tissue to help alleviate the symptoms of atrial fibrillation.For example, the devices above may be used to secure a LAA, ablateatrial tissue in the proximity of the LAA and the pulmonary veins, andto close, and/or occlude, and/or remove the LAA. While the descriptionbelow provides methods of securing, ablating, and excising tissue of theleft atrium and/or LAA, it should be understood that the methods may beused to perform similar procedures on the right atrium, as well as othervascular structures or organs. Similar methods may also be used tosecure, ablate, and excise tissues and/or organs that have one or morecavities therethrough, e.g. stomach, intestine, bladder, etc., for avariety of indications.

III. Methods

Methods for ablating tissue for the treatment of atrial fibrillation maygenerally comprise accessing targeted cardiac tissue regions, advancingablation arrays to the targeted tissue regions, ablating the tissueregions, and withdrawing the ablation arrays once the desired degree oftissue ablation has been attained. Additionally, some methods mayinclude the closure of the left and/or right atrial appendages, whichmay help reduce the risk of thrombosis and may help maintain hemostasis.Some variations of methods for tissue ablation may comprise ablating thetissue from an endocardial surface, an epicardial surface, or both.Ablation devices may access an endocardial surface of the left atriumintravascularly, and/or through the LAA via the pericardial space. Oncethe one or more ablation devices have been placed on the endocardialand/or epicardial surface(s), the ablation devices may be activatedsequentially and/or simultaneously to achieve the desired degree oftissue ablation. Ablation array activation sequences may be repeated asmay be desirable, and may comprise applying ablation energy pulses (fromeither or both of the endocardial and epicardial ablation arrays) ofvarying duration, frequency, duty cycle, power, intensity, etc. Theablation array(s) may be re-positioned to ablate tissue at variousdesired locations. Once all the desired tissue regions have beenablated, the ablation arrays may be withdrawn. In variations where theLAA is used to access the endocardial surface on the left atrium, theLAA may be closed and/or excluded.

Epicardial and Endocardial Ablation

One variation of a method that may be used to electrically isolatetissue in the left atrium and/or LAA is depicted as a flowchart in FIG.8A. Method (800) may be used to ablate tissue from both epicardial andendocardial surfaces using surgical, intravascular and/or otherminimally invasive techniques (e.g., percutaneous, small incisions orports), and may be used in stopped heart or beating heart procedures.The method (800) may comprise gaining access to the pericardial space(802), for example, using the access devices described above.Optionally, a device may be used to locate and stabilize the LAA (804),for example, the closure device (200) as described above and shown inFIG. 2. Once access into the pericardial space and to the LAA has beenestablished, a device may be used to enter the LAA (806), for example,by creating a puncture in the LAA. Additional devices and methods ofusing the LAA as an access port to deliver devices into the heart (e.g.,to contact and/or affect an endocardial surface of the heart) aredescribed in U.S. Provisional Patent Application No. 61/323,816 filedApr. 13, 2010, which was previously incorporated by reference in itsentirety, and U.S. patent application Ser. No. ______ entitled “Methodsand Devices for Accessing and Delivering Devices to a Heart,” filed Apr.13, 2011, which is hereby incorporated by reference in its entirety.Various tissue regions in the left atrium (e.g., atrial wall tissue,tissue at or around the base of the pulmonary veins, tissue within thepulmonary veins, etc.) may be accessed from an endocardial side (810).Devices may be introduced into the left atrium through the LAA, forexample, an endocardial ablation array may be positioned and placed inthe left atrium (812). An epicardial ablation array may be aligned withthe endocardial ablation array (814), for example, based on the positionof the corresponding magnets on the endocardial and epicardial ablationarrays. The epicardial ablation array may be introduced to theepicardial surface of the heart using the same initial access site asthe endocardial ablation array, or may be introduced through a differentaccess site. For example, the endocardial ablation array may beintroduced through a right intercostal site, while the epicardialablation array may be introduced through a left intercostal site.Alternatively, the endocardial and epicardial ablation arrays may bothbe introduced through a left intercostal site, for example. Additionaldescription of access sites are described below. The endocardial andepicardial ablation arrays may be positioned in order to obtain aparticular ablation pattern, after which both ablation arrays may beactivated (816). For example, the endocardial ablation array maycircumscribe the base of the pulmonary veins, while the epicardialablation array may circumscribe the trunk of the pulmonary veins. Afterthe desired tissue regions have been ablated, the ablation devices maybe removed (818), and the LAA may be occluded, closed, and/or removed(820). Once the LAA has been decoupled from the remainder of the leftatrium, all devices may be retracted from the surgical site (822).

As described previously, the endocardial side of the left atrium may beaccessed intravascularly and/or from the LAA via the pericardial space.The access path into the left atrium may be selected based on thetargeted anatomical features in the left atrium such that the pathlength of the catheter and/or ablation devices may be reduced. Theaccess path may also be selected to reduce the maneuvering,manipulating, bending, torquing, etc. that may be required to positionthe catheter and/or devices at the targeted tissue site in the leftatrium. For example, an endocardial ablation device may access the leftatrium using either an intravascular retrograde approach or an antegradetransseptal approach. Entering the left atrium via an intravascularantegrade transseptal approach may allow access to the left pulmonaryveins while reducing the maneuvering, manipulating, bending, torquing,etc. of the distal portion of the device. Entering the left atrium viaan intravascular retrograde approach may allow access to the right andleft pulmonary veins while reducing the maneuvering, manipulating,bending, torquing, etc. of the distal portion of the device.Alternatively or additionally, entering the left atrium through the LAAvia a pericardial approach may allow access to the right pulmonary veinswithout much maneuvering, manipulating, bending, torquing, etc. of thedistal portion of the device. Any of these approaches may be used toposition an endocardial ablation device in the left atrium. In somevariations, a first endocardial ablation array may enter the left atriumthrough an intravascular approach, and a second endocardial ablationarray may enter the left atrium through the LAA via a pericardialapproach.

One example of a method (830) that comprises accessing the endocardialsurface of the left atrium both intravascularly and through the LAA viathe pericardial space is depicted in FIG. 8B. As previously described,an access pathway may be created to the pericardial space (832). A LAAaccess/exclusion device may be used to locate and stabilize the LAA(834). Once access into the pericardial space and to the LAA has beenestablished, a device may be used to create a LAA access site (836),e.g., by puncturing the LAA, which may allow a device to access the leftatrium through the LAA. An intravascular pathway to the left atrium mayalso be attained by advancing a delivery catheter through thevasculature into the left atrium (838), e.g., using a retrograde or anantegrade transseptal approach. Once the intravascular and/or LAA accesspathways into the left atrium have been established, a first endocardialablation array may be advanced into the left atrium through the LAA(840). The first endocardial ablation array may be positioned at anydesired tissue region in the left atrium (e.g., atrial wall tissue,tissue at or around the base of the pulmonary veins, tissue within thepulmonary veins, etc.), such as the tissue along the bases of the rightpulmonary veins (842). The first endocardial ablation array may beactivated to ablate tissue (844). A second endocardial ablation arraymay be advanced intravascularly through the delivery catheter into theleft atrium (846). The second endocardial ablation array may bepositioned at any desired tissue region in the left atrium (e.g., atrialwall tissue, tissue at or around the base of the pulmonary veins, tissuewithin the pulmonary veins, etc.), such as the tissue along the bases ofthe left pulmonary veins (848). The second endocardial ablation arraymay be activated to ablate tissue (850). An epicardial ablation arraymay be advanced via the pericardial space to a location on the outersurface of the heart (852), for example, a location corresponding toeither or both the endocardial ablation arrays (854), and/or alongtissue at or near one or more pulmonary veins, e.g., at or around thetrunks of the pulmonary veins. Additional variations of advancing andpositioning an epicardial device at around the trunks of the pulmonaryveins are described below. In some variations, the endocardial ablationarray(s) and the epicardial ablation array may be positioned oppositeeach other using alignment magnets. Once the epicardial ablation arrayis positioned at the desired location, the epicardical ablation arraymay be activated to ablate tissue (856). The positioning and activationof the epicardial and endocardial ablation arrays may be repeated asdesired. After ablating the desired tissue regions, the ablation arraysmay be removed (858). The LAA may be closed with the access/exclusiondevice (860), and then the access/exclusion device may be removed (862).

While the steps of the method (830) have been described in the sequenceas depicted in FIG. 8B, it should be understood that the steps may takeplace in an alternate sequence, and certain steps may take placesubstantially simultaneously. For example, the delivery catheter may beadvanced intravascularly into the left atrium (838) before or after theLAA access site is created (836). In some variations, the epicardialablation array may be positioned on the epicardial surface of the heart(854) before either or both of the endocardial ablation arrays arepositioned in the left atrium. The activation of the ablation arrays mayoccur sequentially or simultaneously. For example, the first or secondendocardial ablation array and the epicardial ablation array may beactivated simultaneously. Alternatively or additionally, the first andsecond ablation arrays and the epicardial ablation array may all beactivated simultaneously, and/or the first and second ablation arraysmay be activated simultaneously without activating the epicardialablation array. In some cases, the epicardial ablation array may beactivated without activating either or both of the first and secondablation arrays. The method (830) involves the use of two endocardialablation arrays, but in other variations, only one endocardial ablationarray may be used to ablate the left and/or right pulmonary veins. Thesingle endocardial ablation array may be advanced intravascularly orthrough the LAA, as may be desirable.

The methods described above ablate the tissue of the left atrium and/orpulmonary veins from both the endocardial and epicardial surfaces,either simultaneously or sequentially. Placement of the ablation arrayson both the endocardial and epicardial surfaces may help ablate atrialtissue from both sides. Ablating tissue simultaneously from both sidesmay help promote the formation of a lesion that spans a significantportion of the thickness of the tissue between the ablation arrays. Alesion that spans a significant portion of atrial tissue thickness mayhelp to electrically isolate fibrillating tissue. The application ofablation energy (e.g., phase, magnitude, pulse sequence, etc.), type ofablation energy (e.g., radiofrequency, laser, high intensity focusedultrasound, cryogenic agents, microwave energy, heat energy, etc.), andthe shape and size of ablation arrays may be varied according to thegeometry of the tissue and the ablation profile desired. For example,the endocardial ablation array may ablate tissue cryogenically, whilethe epicardial ablation array may ablate tissue with heat energy.Alternatively, the endocardial ablation array may ablate tissue usingheat energy, while the epicardial ablation array may ablate tissuecryogenically. In other variations, the endocardial ablation array mayablate tissue using HIFU, while the epicardial ablation array may ablatetissue using microwaves. The type(s) of ablation energy used and theshape of the ablation array may be selected to limit ablation ofnon-target peripheral tissue.

While the methods and devices described here may be used to ablatecardiac tissue, it should be appreciated that the methods and devicesdescribed here may be adapted to ablate any tissue from any two tissuesurfaces. For example, endocardial and epicardial ablation arrays may beadapted to ablate a tumor cell mass from one or more surfaces.Endocardial and epicardial ablation arrays may also be used to ablatetissue of a hollow organ (e.g., stomach, bladder, lungs, vascularstructures, etc.) by positioning them opposite each other on both theinside and outside surfaces. When two ablation arrays are placed onopposite sides of tissue, they may ablate tissue therebetween in anyvariety of patterns, some of which are shown in FIGS. 9A-9D. Theseablation patterns are described in the context of cardiac structures,however, it should be understood that these patterns may be formed inany desirable tissue, as described above. The ablation profile whenusing both endocardial and epicardial arrays on atrial tissue (900) mayvary depending on the type of ablation energy (e.g. cryo-ablation, highintensity focused ultrasound, radiofrequency, laser, etc.). For example,as depicted in FIG. 9A, a first ablation array (908) may be placed onthe endocardial surface (904) and a second ablation array (906) may beplaced opposite the first ablation array (908) on an epicardial surface(902) of atrial tissue (900). Both the first and second ablation arrays(908, 906) may be simultaneously operated, where the first ablationarray (908) and the second ablation array (906) may deliver ablationenergy at substantially the same time. In some variations, the ablationarrays are operated to deliver ablation energy in-phase, out-of-phase,or at an offset to form the ablation pattern (910). FIG. 9B depicts anablation pattern (920) that may arise when epicardial ablation array(916) delivers ultrasound ablation energy (e.g., HIFU) that may bereflected off endocardial array (918) back to epicardial array (916).Similarly, FIG. 9C depicts an ablation pattern (930) that may be formedwhen endocardial ablation array (928) delivers ultrasound ablationenergy that may be reflected off epicardial array (926) back toendocardial array (928). FIG. 9D illustrates an ablation pattern (940)that may arise when both endocardial ablation array (938) and epicardialablation array (936) reflect the ultrasound ablation energy delivered bythe opposite array.

The ablation pattern created in the tissue may be monitored using one ormore one or more temperature sensors on either or both the endocardialand epicardial arrays. For example, as depicted in FIG. 9E, epicardialablation array (950) and endocardial ablation array (951) may bothcomprise one or more temperature sensors (952) and alignment magnets(954). Both the epicardial and endocardial ablation arrays may comprisetemperature sensors so that a temperature change arising from activatingthe opposite ablation array may be measured, and may be used to indicatethe progress of the ablation of tissue (953). In some variations, atemperature threshold may be set such that reaching or exceeding thattemperature will signal an activated ablation array to deactivate. Thismay be used to prevent excessive or harmful damage to tissue (953). Forexample, the epicardial ablation array (950) may be activated when theendocardial ablation array (951) is not activated. The temperaturesensors of the endocardial ablation array (951) may provide atemperature measurement as a feedback signal to the epicardial ablationarray controller. For example, the duration, magnitude, and othercharacteristics of the ablation energy applied by the epicardialablation array may be regulated based on the temperature measured by thetemperature probe on the endocardial surface of the heart. Theactivation of the endocardial ablation array (951) may be similarlyregulated by temperature feedback using the temperature sensors on theepicardial ablation array. In other variations, temperature sensors mayonly be provided on an ablation array on one side of the tissue, but noton the ablation array on the other side of the tissue. For example, inthe example depicted in FIG. 9F, epicardial ablation array (960) mayhave one or more temperature sensors (962), while endocardial ablationarray (961) may not have any temperature sensors. Both the epicardialand endocardial ablation arrays comprise one or more alignment magnets(964) that may be used to align the arrays with respect to each otheracross tissue (954). The tissue (963) may be clamped between theablation arrays, such that the endocardial ablation array (961) acts asa support for the penetration of the temperature sensors of epicardialablation array (960). The temperature sensors (962) may have a lengththat spans over a substantial thickness of tissue (963), which may allowthe temperature of the middle of tissue (963) to be measured. In somevariations, the temperature sensors of an ablation array may span theentire depth of the tissue, as depicted in FIG. 9G. As seen there, thetemperature sensors (972) of the epicardial ablation array (970) mayspan the entire thickness of the tissue (973) and may, in some cases,even contact endocardial ablation array (971). This may allow thetemperature gradient across the tissue (973) to be measured. Forinstance, it may be determined based on the temperature measurement ifthe tissue is ablated in a uniform manner, etc. Such data may be fedback to an ablation controller to adjust the power, intensity,frequency, magnitude, etc. of the ablation mechanism to attain thedesired ablation pattern. As described previously, the temperaturesensors may be atraumatic or may be tissue-piercing, as may bedesirable.

One variation of a method for ablating tissue from both the endocardialand epicardial surfaces is depicted in FIGS. 10A-10S. Access to thepericardial space may be attained in a variety of ways, some examples ofwhich are shown in FIG. 10A. Additional examples are described in U.S.Provisional Patent Application No. 61/323,801 filed Apr. 13, 2010, whichwas previously incorporated by reference in its entirety, and U.S.application Ser. No. 13/086,328, filed on Apr. 13, 2011, entitled“Methods and Devices for Pericardial Access,” which is herebyincorporated by reference in its entirety. As shown in FIG. 10A, apericardial sac (1002) encases the heart and LAA (1000). Access to theLAA (1000) may be obtained from an initial site located in between ribs,or below the rib cage (1004). For example, the pericardium may beaccessed through a right intercostal site (1006), a left intercostalsite (1008), or a sub-thoracic site (1010), below the costal cartilages.The pericardium may also be accessed from below the diaphragm. In someprocedures, the pericardium may be accessed from multiple sites, forexample, from both right intercostal (1006) and left intercostal (1008)sites, the right intercostal (1006) and sub-thoracic (1010) sites, andthe left intercostal (1008) and sub-thoracic (1010) sites. Depending onthe location of the tissue targeted by one or more of the devicesdescribed herein, the access sites may be selected such that the targettissue region may be readily accessed. For example, an access site maybe chosen for a particular target tissue region such that the tissueregion may be reached by an ablation device without acute bending of thedevice, and/or excessive device maneuvering, manipulating, bending,torquing, etc. In some variations, an access site may be selected toreduce the path length between the initial entry site and the targettissue. Pericardial access may be monitored and/or confirmed using oneor more imaging techniques, for example, fluoroscopy, echocardiography,and endoscopy. Once access to the pericardium has been established andconfirmed, an incision or needle puncture may be made in the pericardialsac (1002), where an incision size may be based in part on the size ofthe device used for entry (e.g., guide wire, cannula, or any of thedevices described here). In some variations, a small incision orpuncture may be initially made and subsequently expanded by dilators toenable entry of other devices. Entry of any device(s) into thepericardial sac (1002) may also be monitored and confirmed using one ormore imaging techniques as described above.

Various devices may be introduced into the epicardial space via anincision or puncture in the pericardium. FIG. 10B depicts a side view ofthe LAA (1000) and the left atrium (1003), encased by the epicardium(1001), myocardium (1005), and pericardial sac (1002). Within the cavityof the left atrium (1003), the bases of two pulmonary veins (1007 a) and(1007 b) may be seen. Devices may be advanced towards the LAA (1000) byinserting guide wire (1014) into a pericardial sac incision (1011). Aguide cannula (1012) may be advanced over the guide wire (1014). A guidecannula (1012) and a guide wire (1014) may be steerable and/orpre-shaped according to a desired access route, for example, an accessroute that enables the penetration of LAA (1000) from between or underthe rib cage. In some variations, one or more dilators may be used toinsert and position the guide cannula (1012), after which the one ormore dilators may be removed. In some variations, the guide wire (1014)may be removed after the guide cannula is positioned. Once in place, theguide cannula (1112) may provide navigational support and guidance to aLAA device, such as the LAA closure device (200) shown in FIG. 2. Onemethod of localizing and stabilizing the LAA (1000) is depicted in FIG.10C, where a LAA stabilizing device (1020) may be advanced via the guidecannula (1012) towards the LAA to contact the LAA. One variation of aLAA stabilizing device (1020) may contact the LAA (1000) by advancing avacuum device (1022) through a looped closure assembly (1024). In thisvariation, the vacuum device (1022) may apply negative pressure whichmay draw a portion of the LAA (1000) into a collector, for example, oneor more lumens, a basket, any woven semi-rigid structure, or a cup(1023), thereby securing the LAA. Some variations of the LAA stabilizingdevice (1020) may also comprise graspers. Graspers may be advancedthrough the looped closure assembly (1024) and such that they may securethe wall of the LAA (1000). Optionally, graspers may penetrate or piercethrough the LAA wall. After the desired level of LAA stability isattained by activating the vacuum device (1022) and/or graspers, thelooped closure assembly (1024) may be advanced over the LAA, and closedover the LAA. In some variations, the looped closure assembly maycomprise a snare loop and a suture loop releasably coupled to the snareloop, where the snare loop and the suture loop may be separatelytightened, and/or tightened in a coordinated fashion. The suture loopmay be released and/or disengaged from the snare loop after the sutureloop has been tightened over the neck of left atrial appendage. In somevariations, the suture loop may be released from the LAA stabilizingdevice (1020) after being closed and locked around the LAA. In somevariations, the looped closure assembly (1024) may be closed tosecure/locate the LAA, and then may be opened to allow devices to beadvanced therethrough, and then closed to secure/locate the LAA. Theopening and closing of the looped closure assembly (1024) may help tomaintain hemostasis during the procedure. Examples of a looped closureassembly and other stabilization and closure devices that may be usedwith the LAA stabilization device (1020), along with other devices andmethods for ensnaring a LAA, are described in U.S. patent applicationSer. No. 12/055,213 (published as U.S. 2008/0243183 A1), which waspreviously incorporated herein by reference in its entirety.

FIG. 10D illustrates the proximal portion of the LAA stabilizing device(1020), which may comprise one or more ports, for example, a vacuumsource port (1021) and a needle port (1030), and actuators (1028 a) and(1028 b). The vacuum source port (1021) and the needle port (1030) maycomprise valves to regulate the passage of devices or fluids through theports. Actuators (1028 a) and (1028 b) may activate the looped closureassembly (1024) and the vacuum device (1022), respectively. While thevacuum device (1022) is activated (e.g. applying negative or positivepressure), an access needle (1032) may be inserted into the needle port(1030). The LAA access device (300) as described above and depicted inFIG. 3 may be used here. As seen in FIG. 10E, an access needle (1032)may be advanced through the needle port (1030), through the LAAstabilizing device, and through the vacuum device (1022) to puncture andenter the LAA (1000). Optionally, before or after the LAA is puncturedby the access needle, looped closure assembly (1024) may be adjusted,e.g. closed or opened, to control bleeding and/or provide endocardialaccess to devices. Other hemostatic devices (e.g., valves, plugs, etc.)may be used at or near the needle puncture to control and/or limitbleeding. Once access needle (1032) has penetrated the LAA, a standardguide wire (1031) may be advanced into the LAA, and the access needlemay be withdrawn. In some variations, the access needle (1032) mayremain in the LAA and left atrium, to maintain the puncture in the LAAand/or left atrium. After the guide wire (1031) is inserted into the LAAand/or left atrium, the vacuum device (1022) may be removed, as shown inFIG. 10F.

Optionally, LAA stabilizing devices may comprise additional LAAattachment features that may further secure the LAA after it has beenstabilized, for example, as depicted in FIG. 10G. As shown there, adistal segment of a LAA stabilizing device (1020′) may comprise a loopedclosure assembly (1024′) and apertures (1025) through which positive ornegative pressure may be applied. Negative pressure may be appliedthrough apertures (1025) to draw the LAA towards the device, furthersecuring and stabilizing it. In this variation, negative pressure may beapplied to apertures (1025) after looped closure assembly (1024′) haseffectively encircled the LAA, which may help ensure that the LAA isfully stabilized prior to the insertion of access needle (1032). Theposition of looped closure assembly (1024′) after it has encircled theLAA may be adjusted by applying positive pressure to the apertures (torelease the LAA) and negative pressure (to secure the LAA).Alternatively, a distal segment (1019) of the LAA stabilizing device(1020′) may be adapted to help looped closure assembly (1024′) to engageand encircle the LAA. For example, the distal segment (1019) may beadvanced towards the LAA. The looped closure assembly (1024′) may thenengage a tip portion of the LAA, after which negative pressure isapplied to the distal-most aperture, while the remaining aperturesremain pressure-neutral. Then, the distal segment (1019) may be advancedtowards the LAA, and then the negative pressure in the distal-mostaperture is released, immediately followed by the application ofnegative pressure on the second distal-most aperture. These steps may berepeated, where distal segment (1019) may effectively advance in astep-wise fashion across the LAA by sequentially applying and thenreleasing negative pressure on each of the apertures (starting from thedistal-most aperture and moving proximally), until the looped closureassembly (1024′) reaches the ostium of the LAA. Once the looped closureassembly (1024′) reaches the ostium of the LAA, it may be cinched tosecure the LAA, and optionally, negative pressure may be applied on allapertures (1025) to further secure the LAA.

Various devices may be advanced over the guide wire (1031) to access theinternal portion of LAA (1000) and left atrium (1003). The guide wire(1031) may be navigated and controlled by actuator (1028 c). Ablationdevices may be advanced over the guide wire (1031) to ablateasynchronous tissue for the treatment of atrial fibrillation. FIG. 10Hdepicts one variation of an endocardial ablation device (1040) as it isadvanced over guide wire (1031), through the wall of the LAA and intothe left atrium. For example, the endocardial ablation device (400) asdescribed above and depicted in FIG. 4 may be used here. In somevariations, an endocardial ablation device may be advanced through theLAA to access the left pulmonary veins. Optionally, an endocardialablation device may be advanced via an intravascular antegradetransseptal approach to access the right pulmonary veins. As describedpreviously, an ablation device such as the endocardial ablation device(1040) may utilize any tissue-affecting mechanism to create a lesion inthe target tissue. Examples of tissue-affecting mechanisms includecryo-ablation, radiofrequency (RF), ultrasound, microwave, laser, anysuitable type of photo-ablation using light-activated agents that maytrigger cellular apoptosis, heat, localized delivery of chemical orbiological agents, and the like. In some variations of an endocardialablation device, a source (1044) may be a reservoir of one or morecryogenic, chemical, or biological agents, and/or may be an energysource (e.g., laser light source, pulse generator, ultrasonic source,etc.) and may be located a proximal portion of the ablation device(1040). A conductive structure (1041) may provide a conduit forconveying the ablation energy from the source (1044) to the distalportion of ablation device (1040). For instance, the conductivestructure (1041) may be a wire, fiber optic cable, lumen, channel,microfluidic channel, etc.

Ablation array (1042) of the endocardial ablation device (1040) may beintegrally formed with the proximal portion of the ablation device(1040), or may be attached via an articulating hinge (1043). In somevariations, an ablation array may comprise ablation elements and/ormagnetic elements, as previously described above. The endocardialablation device (1040) may have a first delivery configuration, wherethe ablation array (1042) has a narrow profile (as shown in FIG. 10H),and a second deployed configuration, where the ablation array (1042)assumes a wider profile (as shown in FIG. 10I). In the deliveryconfiguration, the ablation array (1042) may have a substantiallystraight linear geometry. In the deployed configuration, the ablationarray (1042) may be expanded to have a curved shape, such as asemi-circular shape, to circumscribe the base of pulmonary vein (1007b). The deployed configuration of the ablation array may have any shapethat may be configured to accommodate the anatomy of the target tissueto achieve a desired ablation profile. For example, the ablation arraymay have any of the shapes previously described and depicted in FIGS.6A-6F.

Once the ablation array (1042) of the endocardial ablation device ispositioned at a region of tissue in the left atrium, e.g. around thebase of pulmonary vein (1007 b), an epicardial ablation device may bealigned and placed on the epicardial surface of the atrium (1003). Asecond guide cannula (1052) may be inserted in any of the access sitespreviously described and depicted in FIG. 10A, and may use the same ordifferent access point from the first guide cannula (1012). The guidecannula (1052) may be advanced to the pericardial space as describedpreviously, and once positioned and stabilized, the guide wire (1050)may be advanced through guide cannula (1052) to track around a targettissue region, e.g. the tissue region directly across where theendocardial ablation array (1042) is positioned, as shown in FIG. 10J.Guide cannula (1052) may have one or more curves, and may vary inlength, as suitable for the access site(s) used. Guide wire (1050) maycomprise a magnetic component at its distal tip (not shown). Themagnetic component may be of any suitable type, size, and shape, forexample, the magnet may be a rare-earth, electro-activated, or amulti-alloy (e.g. iron, boron, neodymium) magnet. A guide wire with amagnetic distal tip may facilitate the navigation of the guide wire tothe magnetic component(s) of the positioned endocardial ablation device.The epicardial ablation device may be navigated over the guide wire(1050) and through the guide cannula (1052) to the target site, e.g. ator around pulmonary vein (1017 b) which is directly across from the base(1007 b). In some variations, the epicardial ablation device (500) asdescribed above and depicted in FIG. 5, may be used here. As with theendocardial ablation device, an ablation array (1062) may be attached tothe distal portion of the epicardial ablation device (1060), as shown inFIGS. 10K and 10L. In some variations, an ablation array may compriseablation elements and/or magnetic elements, as previously described withrespect to ablation array (508). Similar to the endocardial ablationdevice (1040), the epicardial ablation device (1060) may have a deliveryconfiguration that has a substantially narrow profile, as seen in FIG.10K, and a second deployed configuration, where ablation array (1062)assumes a wider profile, as seen in FIG. 10L. In the deliveryconfiguration, the ablation array (1062) may have a substantiallystraight linear geometry. In the deployed configuration, the ablationarray (1062) may have a curved shape, such as a semi-circular shape tocircumscribe the trunk of the pulmonary vein (1017 b), however, may beany shape to accommodate the anatomy of the target tissue to achieve adesired ablation profile. In the variation of method described here, thetissue around the pulmonary veins may be ablated both epicardially andendocardially. According to this variation, the shape of the deployedconfiguration of the epicardial ablation device corresponds with theshape of the deployed configuration of the endocardial ablation device,e.g., mirror-symmetric. Once the epicardial ablation device has assumedits deployed configuration, the guide wire (1050) may be withdrawn.

Endocardial and epicardial ablation devices may comprise alignmentfeatures, which may help ensure a particular orientation of one ablationdevice with respect to another, and may also create an intimate contactbetween the ablation devices and the tissue to be ablated. In thevariation of the ablation devices described here, the attractive forcesbetween the magnets on one or both of the epicardial and endocardialablation devices may align the devices to one another. FIGS. 10M and 10Nshow enlarged cross-sectional views of the endocardial ablation array(1042) and the epicardial ablation array (1062) positioned across eachother, where the endocardial ablation array may circumscribe the base ofa pulmonary vein within the cavity of the left atrium, and theepicardial ablation array may circumscribe the trunk of the samepulmonary vein on the outer surface of the left atrium. As shown in FIG.10M, the epicardial ablation device may be advanced such that theepicardial ablation array (1062) is positioned approximately oppositethe endocardial ablation array (1042), i.e. around the pulmonary vein(1017 b) of the left atrium (1003), such as a left pulmonary vein.Endocardial magnetic components (1045) and epicardial magneticcomponents (1065) may attract each other, drawing the ablation arraystowards each other to form a stable contact with the wall of the leftatrium, as shown in FIG. 10N. The magnetic attraction between theablation arrays may compress the wall of the left atrium against theablation arrays, which may improve the efficacy of lesion formation inthe atrial wall, which may reduce the magnitude of the energy (or thequantity of fluid) needed to ablate the tissue between the ablationarrays. In some cases, arranging the ablation arrays on both sides ofthe atrial wall may help form a transmural lesion that spans the entirethickness of the wall between the arrays.

While the devices and methods above are directed towards ablating tissueendocardially and epicardially to form an ablation pattern thatcircumscribes the base of a pulmonary vein, other ablation patterns andprofiles may be also be used for the treatment of atrial fibrillation.Examples of other ablation patterns are schematically illustrated inFIGS. 10O-10P. A cutaway of left atrium (1003) and LAA (1000) revealsthe four pulmonary veins (1007 a), (1007 b), (1007 c), and (1007 d).FIG. 10O depicts one variation of an ablation pattern (1070) where eachof the pulmonary veins are individually circumscribed. FIG. 10P depictsanother ablation pattern (1071) where pairs of pulmonary veins arecircumscribed, i.e., (1007 a) and (1007 c) are circumscribed by onelesion, and (1007 b) and (1007 d) are circumscribed by another lesion.Different pairs of pulmonary veins may be circumscribed together,depending on the profile of electrical isolation that is needed. Theshape (e.g., number of curves, radii of curves, etc.) of the endocardialand epicardial ablation arrays may be adjusted such that ablationpattern (1071) may be obtained. For example, the endocardial andepicardial ablation arrays may have an elongated elliptical shape (e.g.,where the length is substantially greater than the width) to attain theablation pattern of FIG. 10P. FIG. 10Q depicts yet another ablationpattern (1072) where all pulmonary veins are circumscribed by a singlelesion. In this variation, the endocardial and epicardial ablationarrays may be sized and shaped to circumscribe all of the pulmonaryveins. In addition to the lesion patterns described in FIGS. 10O-10Q forpulmonary vein isolation, the endocardial and/or epicardial ablationarrays may be used to create linear lesions through tissue of the leftatrium (LA) including: the LA roof line (e.g., along the connectionbetween the right superior pulmonary vein (1007 b) and the left superiorpulmonary vein (1007 a)), the mitral valve isthmis line (e.g., along theconnection between left inferior pulmonary vein (1007 c) to the mitralvalve annulus (1009)), and the posterior LA line (e.g., along theconnection between both sets of pulmonary veins across the posteriorLA). Other ablation patterns and lesion geometries may be used to obtaina desired degree and profile of electrical isolation. While theseablation patterns have been described in the context of simultaneousablation of tissue from both the endocardial and epicardial surfaces, itshould be understood that these ablation patterns may also be attainedby ablating either the endocardial surface or the epicardial surface. Ingeneral, any appropriate ablation profile may be achieved for any targettissue by adjusting the size and shape of the ablation arrays on theablation devices. For example, to ablate a larger volume and/or area oftissue, a smaller ablation array (e.g. an array that ablates a volume oftissue smaller than the desired ablation pattern) may apply the ablationenergy multiple times at different tissue regions. Alternatively, alarger volume and/or area of tissue may be ablated by an ablation arraythat is comparably sized with the desired ablation volume/area, and maybe shaped according to the target tissue. In this variation, theablation energy may only need to be applied once. While the ablationregions around the pulmonary veins have been described, additionalablation targets for the treatment of atrial fibrillation may includeother anatomical regions. For example, other tissue regions that may besuitable non-pulmonary vein ablation targets may include the superiorvena cava (SVC), LA posterior wall, crista terminalis, coronary sinus(CS), ligament of Marshall, intrarterial septum, and/or any other tissueregions that may trigger atrial fibrillation.

During and/or after tissue ablation, the progress of the ablation andthe lesion size may be monitored and verified. Lesion formation may bemonitored functionally and/or anatomically. For example, lesionformation may be monitored by heat transfer measurements,electrocardiography mapping, ejection fraction, local electrogramamplitude reduction and mapping, impedance tomography, ultrasound,fluoroscopy, and other suitable functional metrics or imagingmodalities. Based on these measurements and images, the rate, size, andother characteristics of lesion formation may be modified, e.g., byadjusting power and wavelength of the ablation energy, to achieve thedesired degree of electrical isolation. In some variations, lesionformation may be measured in terms of the change in the tissuetemperature across the thickness of the tissue. For example, endocardialand epicardial ablation arrays may each comprise temperature sensors aspreviously described may be pressed into the atrial wall tissue tomeasure the temperature on either side of the atrial wall. In somevariations, either the endocardial or the epicardial ablation array hasa temperature probe, so that the heat transfer front from the otherablation array may be measured. The temperature probe may also be aseparate device that is advanced to the desire target tissue region.

Once the desired portion of tissue has been ablated (e.g., verified thata lesion of a desired size and shape has been formed), the ablationdevices and positioning catheters may be removed. The alignment featurethat couples the endocardial ablation array (1042) with the epicardialablation array (1062) may be deactivated, either mechanically (e.g., byapplying a force stronger than, and opposite to, the coupling force) orelectrically (e.g., by turning off the electro-magnet). The endocardialablation device (1040) and the epicardial ablation device (1060) may beremoved sequentially or simultaneously, as may be appropriate. Theendocardial guide wire (1031) may be kept in place to facilitate thenavigation of any additional devices to the left atrium and/or LAA,however, in other variations, the guide wire (1031) may be removed.

Optionally, a method for the electrical isolation of tissue in the LAAand/or left atrium may comprise a step that electrically isolates theLAA. FIG. 10R depicts an occlusion device (1080) that may be advancedover the guide wire (1031) via a guide wire port (1082) and through aworking channel of the LAA stabilizing device (1020) to access theinternal portion of the LAA (1000). For example, the occlusion device(700) as described previously and depicted in FIG. 7 may be used here.In some variations, an occlusion device may be configured to delivercontrast and/or therapeutic agents through the guide wire port or aninfusion lumen that may extend along the occlusion device from theproximal portion to distal portion. The looped closure assembly (1024)may remain in a closed configuration to stabilize and localize the LAA.The distal portion of the occlusion device (1080) may comprise anexpandable member (1086) which may have a collapsed deliveryconfiguration (shown in FIG. 10R) and an expanded deployed configuration(shown in FIG. 10S). Optionally, the distal portion of the occlusiondevice (1080) may also comprise radioopaque and/or echogenic markers(1085) so that the position of the occlusion device may be detected byimaging. Some variations of an occlusion device may comprise sideapertures that provide for the infusion of a contrast agent to enhancevisualization of the occlusion device, or the infusion of other agents,including therapeutic agents such as heparin or other anticoagulants,saline, etc. The expandable member (1086) may be expanded by introducinga fluid, e.g. liquid or gas, via a fluid lumen (1084), from apressurized fluid reservoir (1083). Alternatively or additionally, inother variations of an occlusion device, the expandable member may bemechanically dilated, e.g., by actuating struts. During or after theexpansion of the expandable member (1086), the looped closure assembly(1024) may be further tightened around the LAA by actuating tab (1028d). Tightening the looped closure assembly (1024) around the neck of LAA(1000) may block the exchange of any substances between the LAA cavityand the left atrial cavity. In some variations, tightening the loopedclosure assembly may sever the LAA entirely, such that it is excludedfrom the left atrium. For example, a releasable suture loop and a snareloop of the looped closure assembly may be tightened to exclude the LAA,and the snare loop may be proximally withdrawn from the suture loop,e.g., after the suture loop is released from the looped closure assemblyby further pulling on tab (1028 d). The LAA may be extracted from thebody by any suitable method, for example, by using negative pressure tosecure the LAA into a collector or tubular member, which is thenretracted out of the body. Optionally, a debrider may be used to breakthe excised LAA into smaller portions prior to extraction, which may besuitable for use with a minimally invasive procedure. In somevariations, a chemical or enzyme agent may used prior to extraction tobreak down or soften the LAA for removal.

As described above, the neck of LAA may be encircled and cinched by asuture snare, however, other mechanisms may be included to close and/orocclude the LAA cavity. As shown in FIGS. 11A-11C, a clip (1100) may beused to close the LAA. Clip (1100) may be advanced through a guidecannula and encircled around a LAA or LAA neck. Subsequently, a mandrel(1104) may be advanced through the guide cannula in the direction ofarrow (1006) to urge a collet (1102) onto a clip neck (1103), as shownin FIG. 11A. FIG. 11B depicts that the collet (1102) may continue to beurged in the direction of arrow (1108), until it is completely securedonto the clip (1100), and the LAA enclosed by the clip is tightened. Thecollet (1102) may be engaged onto the clip (1100) by snap-fit,press-fit, or friction-fit. In some variations, alternate closuremechanisms may be used, such as a cable tie with a ratchet mechanism, aNitinol cable or loop, and the like. The clip (1100) may be made ofshape memory material, such as a nickel titanium alloy, where in theunconstrained configuration, the neck (1103) naturally springs open, andthe spring force engages and secures collet (1102). After the collet hassecured and closed the clip, the mandrel (1104) may be removed.

A variety of expandable members may be used to occlude and/or excludethe LAA. For example, an inflatable expandable member, such as a balloonsimilar to the expandable member (1086), may be used to occupy the LAAcavity, preventing the escape of, or continuing development of, thrombiin the LAA. In another variation shown in FIG. 12A, expandable member(1200) in LAA (1000) may be filled with a hardening material (1202),such as thermal polymers, hydrogels, epoxy, and any suitable hardeningmaterials. The hardening material may initially be a liquid or gel thatmay be delivered through a lumen (1204) in the occlusion device, and maysolidify after being deposited in the expandable member (1200) withinthe LAA (1000). Alternatively or additionally, an expandable member maybe self-expanding, as depicted in FIG. 12B. As shown there, anexpandable element (1210) may be an ostial occluder that automaticallyexpands once urged by mandrel (1212) into the LAA cavity. The expandablemember may be made of one or more polymeric materials, for instance,polypropylene, polyurethane, polyethylene, polytetrafluoroethylene, andin some variations, may alternatively or additionally include one ormore metal alloys such as nitinol, stainless steel, etc., or anyshape-memory material. A self-expanding expandable member may be anenclosed structure, such as a balloon, or a mesh-like structure.Mechanisms of self-expansion include shape-memory, thermal expansion,spring-action, and the like.

Endocardial Ablation

While some methods for the treatment of atrial fibrillation may ablatetissue in the left atrium both endocardially and epicardially, othervariations of ablating tissue in the left atrium, and subsequentlyoccluding and/or excising the LAA may be used. One example of a methodthat ablates an endocardial surface of a left atrium is shown in FIG.13A. Method (1300) may be used to ablate tissue from an endocardialsurface using surgical, intravascular and/or other minimally invasivetechniques (e.g., percutaneous, small incisions or ports), and may beused in stopped heart or beating heart procedures. The method (1300) maycomprise accessing the pericardial space (1302). Optionally, a devicemay be used to locate and stabilize the LAA (1304), for example, theclosure device (200) as described above and shown in FIG. 2. Once accessinto the pericardial space and to the LAA has been established, a devicemay enter the LAA (1306) by creating a puncture in the LAA. Access tovarious tissue regions in the left atrium (e.g., atrial wall tissue,tissue at or around the base of the pulmonary veins, tissue within thepulmonary veins, etc.) from an endocardial side may be established(1310). An endocardial ablation array may be positioned and placed alongan endocardial surface of the left atrium (1312). For example, theendocardial ablation array may circumscribe the pulmonary veins toobtain a particular ablation pattern. The endocardial ablation array maythen be activated (1314). After the desired tissue has been ablated(e.g., atrial wall tissue, tissue at or around the base of the pulmonaryveins, tissue within the pulmonary veins, etc.), the ablation devicesmay be removed (1316), and the LAA may be occluded, closed, and/orremoved (1318). Once the LAA has been decoupled from the remainder ofthe left atrium, all devices may be retracted from the surgical site(1320). In some variations of methods for ablating tissue in the leftatrium, the endocardial ablation device may be advanced intravascularly(e.g., from a retrograde approach, or an antegrade transseptal approach,etc.). Access to the left atrium may be accessed by any method orapproach as may be suitable for contacting the targeted tissue region.

While the method described above uses one endocardial ablation array forablating the tissue of the left atrium from an endocardial side, othermethods may use two endocardial ablation arrays. One example of a methodthat uses two endocardial ablation arrays for ablating atrial tissue onan endocardial side is depicted in FIG. 13B. As previously described, anaccess pathway is created to the pericardial space (1332). A LAAaccess/exclusion device may be used to locate and stabilize the LAA(1334). Once access into the pericardial space and to the LAA has beenestablished, a device may be used to create a puncture in the LAA(1336), which may allow a device to access the left atrium through theLAA. An intravascular pathway to the left atrium may also be attained byadvancing a delivery catheter through the vasculature into the leftatrium (1338), e.g., using a retrograde or an antegrade transseptalapproach. Once the intravascular and/or LAA access pathways into theleft atrium have been established, a first endocardial ablation arraymay be advanced into the left atrium through the LAA (1340). The firstendocardial ablation array may be positioned at any desired tissueregion (e.g., atrial wall tissue, tissue at or around the base of thepulmonary veins, tissue within the pulmonary veins, etc.), such as alongtissue at or around the bases of the right pulmonary veins (1342). Thefirst endocardial ablation array may be activated to ablate tissue(1344). A second endocardial ablation array may be advancedintravascularly through the delivery catheter into the left atrium(1346). The second endocardial ablation array may be positioned alongtissue at or around the bases of the left pulmonary veins (1348). Thesecond endocardial ablation array may be activated to ablate tissue(1350). The positioning and activation of the first and secondendocardial ablation arrays may be repeated as desired. After ablatingthe desired tissue regions, the ablation arrays may be removed (1352).The LAA may be closed with the access/exclusion device (1354), and thenthe access/exclusion device may be removed (1356).

While the steps of the method (1330) have been described in the sequenceas depicted in FIG. 13B, it should be understood that the steps may takeplace in an alternate sequence, and certain steps may take placesubstantially simultaneously. For example, the delivery catheter may beadvanced intravascularly into the left atrium (1338) before or after theLAA access site is created (1336). In some variations, the secondablation array may be advanced through the delivery catheter into theleft atrium (1346) before the first endocardial ablation array isadvanced through the LAA into the left atrium. The activation of theablation arrays may occur sequentially or simultaneously. For example,the first or second endocardial ablation array may be activatedsimultaneously or sequentially.

Examples of ablation patterns that may be formed by endocardial ablationmethod (1300) are shown in FIGS. 14A and 14B. Ablation array (1402) ispositioned against atrial wall (1400) on the endocardial side (1404).The ablation energy (1403) may be any mechanism of tissue ablation, asdescribed previously. As depicted in FIG. 14B, the portion of the atrialwall (1405) that is closest to ablation array may be ablated relativelyquickly, while the portion of the atrial wall further from the ablationarray, e.g. tissue near the epicardial side (1406), may not be ablated.To ablate tissue furthest from the ablation array (1402), a longerexposure to a greater quantity of ablation energy (1403) may be needed.For example, to ablate tissue closest to the epicardial side (1406),radiofrequency or cryogenic delivery may need to be increased, and laserenergy and heat may need to be more intense. Additionally oralternatively, the ablation of tissue further from the ablation array(1402) may involve increasing the exposure time of tissue (1400) to theablation energy (1403). The ablation depth achieved an ablation arraymay be regulated by adjusting more of the above-described factors, asmay be desirable. For example, the depth of tissue that is ablated maybe 5%, 10%, 25%, 40%, 50%, 60%, 75%, 80%, 95%, etc. of the thickness ofthe tissue wall. In some variations, closed system or open systemirrigation may be included during the delivery of the energy source toregulate the ablation of tissue adjacent to the ablation array. Asdescribed previously a temperature probe may be used to measuretemperature changes that may arise from tissue ablation, which may helpto regulate the amount of ablation applied to a tissue region.

Epicardial Ablation

Ablation of tissue of the LAA and left atrium may be achieved byepicardial ablation. An example of a method (1500) for epicardialablation is shown in FIG. 15. Method (1500) may be used to ablate tissueusing surgical techniques or intravascular techniques, and may be usedin stopped heart or beating heart procedures. As previously described,an access pathway may be created to the pericardial space (1532). Anepicardial ablation array may be advanced via the pericardial space tothe outer surface of the heart (1534). The epicardial ablation array maybe positioned along tissue at or near the trunk of the pulmonary veins(1536). The epicardial ablation array may be activated to ablate tissue(1538). Optionally, the epicardial ablation array may be positioned andactivated at different locations on the outer surface of the heart, asmay be desirable. After ablating the desired tissue regions, theablation arrays may be removed (1540). Optionally, a LAAaccess/exclusion device may be advanced to the LAA via the pericardialspace (1542). The access/exclusion device may be used to locate andstabilize the LAA (1544). The LAA may be occluded or excised by theaccess/exclusion device (1546), and then the access/exclusion device maybe removed (1548). Decoupling the LAA from the remainder of the leftatrium may help reduce the risk of thrombosis or stroke that may occurin atrial fibrillation.

FIGS. 19A-19F depict another variation of an access device and methodthat may be used to position a device on an epicardial surface of theheart, e.g., around a tissue structure such as a blood vessel or theLAA. Access device (1900) or a similar device may be used to place aguide element (1902) or other device around a tissue structure (1904),such as a blood vessel or the left atrial appendage. As shown there,access device (1900) may comprise a cannula (1906), a first guide(1908), and a second guide (1910). First (1908) and second (1910) guideseach may comprise a lumen (1912) extending therethrough, and may furthercomprise a magnetic alignment element (1914) at a distal end thereof.First (1908) and second (1910) guides may be at least partially housedinside cannula (1906), and may be configured to be advanced out of adistal end of the cannula (1906). In some variations, first (1908) andsecond (1910) guides may be housed in a single lumen (not shown) ofcannula (1906). In other variations, first (1908) and second (1910)guides may be housed in separate lumens (e.g., a first lumen and asecond lumen, respectively). It should be appreciated that cannula(1906) may comprise any suitable number of lumens (e.g., one, two, orthree or more).

Returning to the figures, cannula (1906) may be advanced to tissuestructure (1904), as shown in FIG. 19A. In some variations, the tissuestructure (1904) may be the right atrial appendage. Cannula (1906) maybe advanced in any suitable manner. In some variations, cannula (1906)may be advanced over a guidewire (e.g., via one or more lumens of thecannula (1906). Additionally or alternatively, one or more portions ofthe cannula (1906) may be steerable. While shown in FIGS. 19A-19F asbeing a blood vessel (1905), tissue structure (1904) may be any suitableanatomical structure. In some variations, tissue structure (1904) may bethe left atrial appendage.

Once cannula (1906) is positioned at or near the tissue structure(1904), first guide (1908) may be advanced out of the distal end ofcannula (1906), as shown in FIG. 19B. As first guide (1908) is advancedout of the distal end of cannula (1906), it may take on a curvedconfiguration. In some variations, the first guide (1908) has apre-shaped curved configuration, which may be constrained when it ishoused within cannula (1906). In other variations, the first guide(1908) may be steered or otherwise actuated to take on the curvedconfiguration. The first guide (1908) may be advanced such that a distalportion of the guide (1908) curves at least partially around the tissuestructure (1904), as depicted in FIG. 19B.

The second guide (1910) may then be advanced from the distal end ofcannula (1906), as depicted in FIG. 19C. As shown there, the secondguide (1910) may be advanced toward and may engage the first guide(1908). For example, in variations where the first (1908) and second(1910) guides each comprise a magnetic alignment element (1914), themagnetic alignment elements (1914) of the first (1908) and second (1910)guides may attract each other and hold the distal ends of the two guidesin place relative to each other. In some variations, the distal ends offirst (1908) and second (1910) guides may be positioned such that thelumens (1912) of the two guides are aligned. In some of thesevariations, the magnetic alignment elements (1914) of each of the first(1908) and second (1910) guides may hold the lumens (1912) of the twoguides in alignment.

Once the lumens (1912) of the first (1908) and second (1910) guides arealigned, a guide element (1902) may be advanced through the lumen (1910)of first guide (1908) such that it exits the distal end of first guide(1908) and enters the lumen of the second guide (1910) (or vice versa).The guide element (1902) may then be advanced through the second guide(1910) (or the first guide (1908)) and the first (1908) and second(1910) guides may be withdrawn through the cannula, as shown in FIG.19D. In some instances, both ends (not shown) of the guide element(1902) may extend out from a proximal end of the cannula and/or mayextend outside of the body. In these variations, guide element (1902)may be a wire, a suture, yarn, strand, or the like. While FIGS. 19A-19Ddepict advancing a guide element (1902) through lumens (1912) of thefirst (1908) and second (1910) guides, it should be appreciated that insome variations, a tube or catheter may be advanced over the first(1908) and second (1910) guides to place the tube or catheter around thetissue structure (1904).

In some variations, the ends of the guide element (1902) may be pulledproximally to cinch the distal exposed portion of guide element (1902)(e.g., the portion of guide element extending from the distal end ofcannula (1906)) around the tissue structure (1904), as shown in FIG.19E. In variations where tissue structure (1904) is the left atrialappendage (not shown), cinching guide element (1902) around the leftatrial appendage may act to close the left atrial appendage (temporarilyor permanently). In variations where the left atrial appendage is usedas an access port into the interior of the heart, as describedhereinthroughout, guide element (1902) may be used to help providehemostasis by temporarily closing the left atrial appendage around oneor more devices placed through tissue of the left atrial appendage.Additionally or alternatively, in some variations, a knot, clip, orclamping structure (not shown) may be advanced over a portion of theguide element (1902) to hold the guide element in place around thetissue structure (1904). In variations where the guide element (1902) isplaced around the left atrial appendage, the guide element (1902) may beused to close the left atrial appendage (as described immediatelyabove). For example, a knot, clip, or clamping structure may be advancedover the guide element (1902) to hold it in place such that the leftatrial appendage is held in a closed configuration. In some variations,the guide element may comprise a releasable suture loop, where cinchingthe guide element around the tissue structure (1904) likewise cinchesthe suture loop around the tissue structure (1905). Once the desiredlevel of tightening is achieved, the suture loop may be released fromthe guide element, and the guide element may be retracted proximally. Tosecure the tension in the suture loop, a knot, clip or other clampingstructure may be advanced through the cannula to lock the suture loop.In some variations, a suture-cutter or the like may be advanced over aportion the guide element (1902) or suture loop to sever at least aportion of the guide element (1902) or suture loop (e.g., the portionsof guide element located proximal to the knot, clip, or clampingstructure.)

Additionally or alternatively, one or more devices may be advanced overthe guide element (1902) to place the device at or around the tissuestructure (1904). In some variations, one or more ablation devices maybe advanced over the guide element, such as ablation device (1918) shownin FIG. 19F. As shown there, ablation device (1918) may comprise one ormore ablation elements (1920) and one or more magnetic elements (1922),and may be any of the ablation devices previously described.Additionally or alternatively, access device (1900) may also be used toplace measurement electrodes, temperature sensors, and the like at oraround the pulmonary veins, the LAA, and/or any tissue structure on theepicardial surface of the heart. The devices and methods depicted inFIGS. 19A-19F may be used in combination with any of the devices andmethods previously described (e.g., in combination with the methodsdepicted in FIGS. 8A and 8B, FIG. 15, etc.).

Examples of ablation patterns that may be formed by epicardial ablationmethod (1500) are shown in FIGS. 16A and 16B. Ablation array (1602) ispositioned against an atrial wall (1600) on the epicardial side (1604).The ablation energy (1603) may be any mechanism of tissue ablation, asdescribed above. The portion of atrial wall tissue (1600) that isclosest to ablation array (1602) may be ablated relatively quickly,while tissue further from the ablation array, e.g. tissue near theendocardial side (1606), may not be ablated. To ablate a targeted tissuefurthest from ablation array (1602), such as targeted tissue (1607)depicted in FIG. 16B, a longer exposure to a greater quantity ofablation energy (1603) may be needed. For example, to ablate tissueclosest to the endocardial side (1606), ultrasound and radio frequenciesmay need to be increased, and laser energy and heat may need to be moreintense. Additionally or alternatively, the ablation of tissue furtherfrom ablation array (1602) may involve increasing the exposure time ofatrial wall (1600) to the ablation energy (1603). Depending on the typeof ablation energy (1603) and/or the quality of the tissue (e.g.,thermal energy conductivity, etc.), greater quantities of ablationenergy may successfully ablate the targeted tissue (1607) withoutburning, charring, and/or coagulation of the tissue closest to theablation array. For example, ultrasound ablation may be shaped andfocused such that more energy is delivered to the targeted tissue (1607)than to the tissue on the epicardial side (1604). In some variations,closed system or open system irrigation may be included during thedelivery of the energy source to limit the heating of tissue adjacent tothe ablation array, while delivering larger quantities of energy totissue further away from the ablation array. As described previously atemperature probe may be used to measure temperature changes that mayarise from tissue ablation, which may help to regulate the amount ofablation applied to a tissue region.

IV. Systems

Also described herein are systems for affecting tissue within a body toform a lesion. In general, the systems may comprise devices that haveone or more tissue-affecting elements, together with additionalcomponents that help to locate and secure the target tissue. Forexample, the system may comprise a first and second device, where eachof the devices comprises an elongate member and one or moretissue-affecting elements. The first and second devices may be separatefrom each other, but have corresponding geometries and sizes so thatoperating the tissue-affecting elements may form a lesion in the tissuebetween them. These devices may have any geometry (e.g., size, number ofcurves, radii of curvature, etc.), one or more configurations (e.g., adelivery configuration and a deployed configuration) and may apply avariety of tissue-affecting mechanisms (e.g., cryogenic substances,lasers, high intensity focused ultrasound, radiofrequency energy, heat,microwave, etc.). The tissue-affecting elements for a given device maydeliver a combination of one or more types of tissue-affectingmechanisms. The tissue-affecting elements may be any of the ablationelements previously described. Some devices may also comprise magneticcomponents so that the attractive force between the magnets may causethe first and second devices to be positioned in a certain orientationwith respect to each other, e.g. opposite one another. Systems may alsoinclude actuators and controllers that regulate the application of thetissue-affecting mechanisms. For example, tissue-affecting elements maybe configured to be operated simultaneously, and/or apply energy to thetissue in a pre-programmed manner. A controller may be coupled to thetissue-affecting elements to synchronize their operation temporally(e.g., to affect tissue in-phase or out-of-phase, synchronously orasynchronously) and spatially (e.g., to affect one region of tissuewithout affecting another, to affect one region of tissue from more thanone surface, etc.). In some variations, a controller may be configuredto receive temperature data measured at the target tissue site toregulate the operation of the tissue-affecting elements.

Some systems for affecting tissue within a body may include devices thataid in accessing and securing the tissue, as well as positioning thetissue-affecting elements with respect to the tissue. For example, somesystems may comprise a closure device (such as described above) may beincluded to locate and secure target tissue, a piercing member, one ormore guide cannulas, and one or more guide wires. These devices may beconfigured to be inserted through, or advanced over, each other, whichmay be desirable for minimally invasive procedures.

Although the foregoing invention has, for the purposes of clarity andunderstanding been described in some detail by way of illustration andexample, it will be apparent that certain changes and modifications maybe practiced, and are intended to fall within the scope of the appendedclaims.

1. A system for affecting tissue within a body comprising: a firstdevice comprising a first elongate member and one or moretissue-affecting elements; a second device that corresponds to the firstdevice, the second device comprising a second elongate member and one ormore tissue-affecting elements that correspond to the one or moretissue-affecting elements of the first device, wherein the second deviceis separate from the first device, and wherein the tissue-affectingelements of the first and second devices are configured to operatesimultaneously to form a tissue lesion at least partially therebetween.2. The system of claim 1, wherein the first and second devices comprisea magnetic component.
 3. The system of claim 2, wherein the first andsecond devices each have a one or more temperature sensors.
 4. Thesystem of claim 3, wherein the first and second devices have a firstdelivery configuration and a second deployed configuration, wherein thedevices are compressed in the first delivery configuration and thedevices are expanded in the second deployed configuration.
 5. The systemof claim 4, wherein the first and second devices has one or more curvesin the second deployed configuration.
 6. The system of claim 1, whereinthe tissue-affecting elements are configured to deliver cryogenicsubstances.
 7. The system of claim 1, wherein the tissue-affectingelements are configured to deliver high intensity focused ultrasound. 8.The system of claim 1, wherein the tissue-affecting elements areconfigured to deliver heat energy.
 9. The system of claim 1, wherein thetissue-affecting elements are configured to deliver microwave energy.10. The system of claim 1, wherein the tissue-affecting elements areconfigured to deliver radiofrequency energy.
 11. A method of affectingtissue within a body comprising: advancing a first device comprisingtissue-affecting elements to a first surface of a target tissue, whereinthe first tissue-affecting device is positioned against a portion of thefirst surface of the target tissue; advancing a second device comprisingtissue-affecting elements to a second surface of the target tissue,wherein the second surface is opposite the first surface of the targettissue; positioning the first and second devices such that ablationenergy passes through the target tissue between the tissue-affectingelements of the first and second devices; operating the tissue-affectingelements of the first and second devices simultaneously such that alesion is formed in the target tissue.
 12. The method of claim 11,wherein advancing the first device comprises inserting a curved sheathat a location beneath a sternum and advancing the first device throughthe sheath.
 13. The method of claim 11, wherein the positioning stepcomprises positioning the first and second ablation devices using one ormore magnetic components.
 14. The method of claim 11, wherein the targettissue is cardiac tissue.
 15. The method of claim 11, wherein the targettissue is gastrointestinal tissue.
 16. The method of claim 11, whereinthe target tissue is a cancerous cell mass.
 17. The method of claim 11,further comprising verifying that the formed lesion spans between thefirst and second tissue-affecting devices.
 18. The method of claim 17,wherein the verifying step comprises assessing the lesion usingelectrical impedance tomography.
 19. The method of claim 17, wherein theverifying step comprises assessing the lesion using thermal imagingtechniques.
 20. A method of forming a lesion in the tissue of a leftatrium comprising: advancing a first tissue-affecting device into theleft atrium through a puncture in a left atrial appendage, wherein thefirst tissue-affecting device is positioned against the atrial wall;advancing a second tissue-affecting device to an external atrial wall,wherein the second tissue-affecting device is positioned against theexternal atrial wall opposite the first tissue-affecting device;positioning the first and second tissue-affecting devices such thatablation energy may pass between them; operating the first and secondtissue-affecting devices simultaneously such that a lesion is formed inthe atrial wall at least partially therebetween; and isolating the leftatrial appendage.
 21. The method of claim 20, wherein advancing thefirst tissue-affecting device further comprises advancing a first guidewire through a puncture in the left atrial appendage into the leftatrium, and advancing the first tissue-affecting device over the firstguide wire.
 22. The method of claim 21, wherein advancing the secondtissue-affecting device further comprises advancing a second guide wireto the external atrial wall, and advancing the second tissue-affectingdevice over the second guide wire.
 23. The method of claim 22, whereinthe positioning step comprises positioning the first and second ablationdevices using one or more magnetic components.
 24. The method of claim20, wherein isolating the left atrial appendage comprises positioning anocclusion device comprising a rounded disc with one or more groovescircumscribing the outer perimeter of the disc, wherein the disc issized and shaped to be constrained in base of the left atrial appendage.25. A kit for affecting tissue within a body comprising: a first devicecomprising one or more tissue-affecting elements and a longitudinallumen therethrough, wherein the first device has a first compressedconfiguration and a second expanded configuration; a second device thatcorresponds to the first device, the second device comprising one ormore tissue-affecting elements and a longitudinal lumen therethrough,wherein the second device is separate from the first device, and whereinthe tissue-affecting elements of the first and second devices areconfigured to operate simultaneously to form a tissue lesion at leastpartially therebetween.
 26. The kit of claim 25, wherein the firstdevice and the second device further comprise one or more magneticcomponents.
 27. The kit of claim 25, further comprising a closure devicecomprising an elongate body and a distal snare, wherein the elongatebody comprises a lumen therethrough.
 28. The kit of claim 27, furthercomprising a piercing member configured to be advanced through theelongate body lumen.
 29. The kit of claim 26, further comprising a firstand second cannula.
 30. The kit of claim 27, further comprising a firstand second guide wire.